At the stroke of midnight Monday, just as Pennsylvania expanded coronavirus vaccine eligibility, Anna Rutledge began the online search to get an appointment for a newly eligible frontline worker.

The 33-year-old Glenside woman lucked out: She quickly got a Wednesday spot at a Sellersville pharmacy for her husband, Nathaniel Levan, 37, who has reported to his Horsham manufacturing company since the spring.

The “reason it worked was because I was up late” on Easter night, she said, when she thought demand might be light. And the only reason she knew the intricacies of the state’s patchwork system so well, she added, was because she got laid off due to the pandemic and has spent free time vaccine-hunting for her 70-year-old father.

Rutledge is among hundreds of thousands of Pennsylvanians who this week joined the race to snatch up shot appointments before the next group joins the eligibility pool. The state’s 1C group joins on April 12, and appointments will open to all people 16 and older on April 19.

Gov. Tom Wolf said Wednesday that officials are estimating that everyone in the state who wants a shot will have gotten at least a first dose by the second week of May. That estimate could change because both supply and demand are fluctuating.

» READ MORE: All adults in Pa. eligible for COVID-19 shot on April 19; Philly suburbs will give out J&J shots as state backs off mass clinic plan

The state estimates that 700,000 to one million frontline workers — including public transit employees, clergy, postal service employees, and people who work in manufacturing — became eligible Monday as members of phase 1B.

And more will follow: Between 1.3 million and 1.7 million essential workers in 1C will be eligible April 12, leaving between 3.1 and 3.9 million people who will join the pool April 19.

They join about four million Pennsylvanians, including two million seniors and others with high-risk conditions, who have been eligible for months as part of phase 1A (these numbers do not include Philadelphia). People in 1A remain eligible, and as universal eligibility quickly approaches, President Joe Biden this week urged seniors who have not yet been vaccinated to sign up for shots as soon as possible.

All adults will be eligible on April 19 in both Philadelphia, which is distributing vaccine independent from the state, and New Jersey, as well, following a directive from Biden.

» READ MORE: Philadelphia joins Pa., N.J. in opening COVID-19 vaccination to all adults by April 19, by Biden’s request

When Pennsylvania announced the rapid expansion of eligibility last week, many residents felt a sense of relief. But questions remained: How difficult will it be to get appointments when eligibility expands? How far in the future will those appointments be? Will the vaccine supply be able to keep up with the high demand in the densely populated Philadelphia suburbs?

At briefings this week, Wolf said he didn’t expect the appointment backlogs that occurred in phase 1A, saying the federal vaccine supply was “in a very different place” now.

“With less than a million in 1B and less than 2 million in 1C, we are giving ourselves a little time, and we have a lot more supply, so I’m hoping that we don’t — and we’re planning not to — have the surprises and the logjams we had the first time around,” the governor said Wednesday. “We think we can do this.”

» READ MORE: Pa. is finally expanding vaccine eligibility. But perceptions of a rocky rollout linger.

The governor said expanding eligibility in phases, even over a short period of time, made more sense than opening it to the general public all at once, and would help prevent backlogs.

On Wednesday, Wolf visited a vaccine clinic in Allegheny County, while acting Health Secretary Alison Beam went to one in Allentown. Both said the state is working to address vaccine equity and hesitancy.

“Supply has not at all met demand statewide,” said Beam, who noted that the state is getting only 20,000 Johnson & Johnson doses next week compared with nearly 170,000 this week. But “hesitancy is becoming our focus. We’re getting to the point where we are finding that folks may have the appointment acceptable to them, but they may have those reservations” about safety and efficacy.

» READ MORE: As Americans scramble to get vaccinated, many rural, conservative Pennsylvanians feel no urgency

More than a third of Pennsylvanians — 35.4% — have received at least a first dose, they said, with the state hitting 11th in national rankings on Wednesday, according to a New York Times tracker of Centers for Disease Control and Prevention data.

The collar counties got double shipments of single-dose Johnson & Johnson this week, officials said, to help them vaccinate the remaining residents in 1A. Montgomery County will open two more clinics Friday in Lansdale and Pottstown, and Bucks County opened one in Warwick.

In Montgomery County, 3,122 people had preregistered for 1B since Monday, and County Commissioner Val Arkoosh said she expected them to start being given appointments at the end of this week or early next week. How quickly appointments get made for people in 1B and then 1C depends on how many residents in 1A fill up the county’s slots.

“We want to encourage people [in 1A, 1B, and 1C] to register. This large number of vaccines is going to allow us to move through our list very quickly, so people might be quite pleasantly surprised,” Arkoosh said.

Chester County gave 24,202 people in 1B who had preregistered with the Health Department access to schedule appointments on Monday morning. Bucks County also sent more than 50,000 people on their waiting list links to sign up on Tuesday; appointments may be scheduled six to eight weeks out, a spokesperson said.

Delaware County began scheduling people in 1B on Monday and is still working through 1A. The county opened up a few thousand appointments for its clinics Tuesday night, a spokesperson said, and they were booked within a couple of hours.

There have been hiccups elsewhere. Pharmacies that get their vaccine supply straight from the federal government can’t update their eligibility requirements online until the CDC tells them to do so, said Rite Aid spokesperson Chris Savaresi. Some Pennsylvanians now eligible in phase 1B reported that online schedulers for these pharmacies didn’t allow them to access appointments. The CDC did not respond to an inquiry.

Meanwhile, concerns remained that some people in phase 1A could be left behind as others rush for shots. “My fear,” said Angie Allen, 46, of West Grove, whose senior in-laws just got their first doses Tuesday, “is people like them are going to be lost in the shuffle.”

» READ MORE: Pa. seniors are ‘at their wit’s ends’ trying to get coronavirus vaccines

In Huntingdon Valley earlier this week, Kathleen Sannicks-Lerner, 60, said she felt angry and frustrated that she still couldn’t find a shot for her husband, Arthur Lerner, a 64-year-old with severe cardiac issues. She has signed up with Montgomery County and tried a local Giant. Over the last week, she called the Pennsylvania Department of Health several times, she said, but never heard back.

“We are at a loss,” said Sannicks-Lerner, a Philadelphia teacher who was vaccinated through the district’s program. “This was done so poorly. ... Why couldn’t we just go to his physician?”

But with supply increasing there are signs of optimism.

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John Capone, 34, of West Chester was one of the 24,000 people eligible in 1B who got an email from Chester County on Monday, allowing him to schedule his appointment. An engineer in the manufacturing sector, Capone secured a slot for next week, said his wife, Julia Capone, who preregistered him on the county website last week.

“I know a lot of people have had trouble getting appointments and the county hasn’t had as much vaccine supply as they were hoping, so I was really pleasantly surprised,” said Julia Capone. “I’m just really grateful that the process went smoothly.”

“It feels hopeful,” she added. “Kind of like the end is in sight, maybe.”