The European Union is to start Covid-19 inoculations on 27 December, European Commission President Ursula von der Leyen said.
"It's Europe's moment. On 27, 28 and 29 December vaccination will start across the EU," she tweeted.
Ms von der Leyen had previously called for a coordinated start to inoculations on the same day in all 27 EU countries.
The European Medicines Agency (EMA) said an expert panel will convene on Monday to evaluate the Pfizer/BioNTech vaccine. It hasn't yet been approved for use in the EU.
Deliveries will start on 26 December from vaccine production sites in Belgium and Germany but the commission said it would be up to each of the EU's 27 states to organise and coordinate their own vaccination programmes.
Meanwhile, in the United States, a panel of experts has voted to recommend emergency approval of Moderna's Covid-19 vaccine, paving the way to start shipping six million doses as soon as this weekend.
The Food and Drug Administration is now expected to imminently grant an emergency use authorisation, which would make Moderna's vaccine the second to be approved in a western country.
The EU is carrying out a coordinated vaccination programme across its 27 member states to ensure fair access to doses.
Member states will decide who gets priority for the injections, but the elderly and healthcare workers treating Covid-19 patients will be at the front of the queues.
Italy's health ministry said it expects to begin vaccinating on 27 December.
Italy is set to receive an initial 1.83 million doses from Pfizer. The first inoculations will be administered to health workers, a statement said.
However, health officials in the Netherlands said they could not yet say whether it would be among the first EU countries ready to start with vaccinations in December.
The European Commission has sealed contracts with seven suppliers of potential vaccines to ensure all adult EU citizens will eventually be able to be inoculated.
Preliminary talks between the EU and US firm Novavax have concluded with an agreement to secure up to 200 million doses of its Covid-19 vaccine.
"The envisaged contract foresees the possibility for member states to buy 100 million doses with the option of buying another 100 million doses," an EU spokesman said.
The UK and the US are already inoculating people with that vaccine under emergency national authorisations.