(CNN) — The new government website where people can order free Covid-19 at-home rapid antigen tests is up and running. With just names and addresses, families can go to COVIDtests.gov and request up to four free tests to be delivered to their homes.

The website comes online as the Biden administration faces growing pressure to fix the coronavirus testing shortage amid the Omicron surge. The White House says it already has tens of millions of tests ready to go. It is spending $4 billion to deliver the first 500 million tests to homes across the US.

The program passes the testing pressure to the US Postal Service, which says it’s prepared to deliver.

“We have been working closely with the Administration and are well prepared to accept and deliver test kits on the first day the program launches,” Postmaster General Louis DeJoy said in a statement.

But right now, the Postal Service is facing problems, with communities in several states dealing with mail delays because of Omicron.

As of Tuesday, more than 19,200 postal workers were either sick from Covid-19 or quarantining, just shy of the agency’s pandemic high last January and more than twice as many as just two weeks ago, according to the American Postal Workers Union.

Mail delays

Late last week, mail was delivered to Derek Reynolds’ Maryland home for the first time in nearly three weeks.

“It’s a very weird and frustrating situation to have things you know are coming but you just don’t know when they are ever going to arrive,” Reynolds said. “I would be very worried about getting a test in any kind of timely manner.”

Last week, Del. Eleanor Holmes Norton sent a letter to the Postal Service raising concerns about mail delays in DC and layoffs at USPS.

“There are households where there has been no mail delivered for days,” the DC Democrat said. “If we can’t get the mail, how are we going to get these Covid tests?”

The Postal Service is now ramping up operations. It’s setting up 43 centers that will pack and ship the tests and is hiring more than 7,000 temporary workers, many of whom were brought on for the holidays, according to the American Postal Workers Union.

USPS defended its service performance during the Omicron surge in a news release last week, saying 90% of first-class mail had been delivered on time in the first week of January.

“The Postal Service’s mitigation plans continue to perform well,” the release states. It declined to provide CNN any further comment or logistical plans.

Shipping of test kits

But even if all goes right, don’t expect overnight delivery. The White House predicts most tests will ship in seven to 12 days, and not until late January.

The Biden administration says the tests should be used in three situations: if you have Covid-19 symptoms; at least five days after exposure; or before gathering indoors with unvaccinated people or those at higher risk for Covid-19.

Dr. William Schaffner, an infectious disease expert who is part of the US Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices, is advising Americans to request the tests before they need them.

“If they wait until they have an issue, by the time the tests arrive, the optimal time for testing may well have passed,” Schaffner said. “If you’ve been exposed and you don’t have the tests available, you’ll have to find testing resources elsewhere.”

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