It is still the Welsh Government's aim to reach a UK-wide agreement on Covid-19 rules for the Christmas period, the health minister has said.
Vaughan Gething's comments come after Downing Street said Boris Johnson was expected to make an announcement on Christmas to MPs on Monday.
Mr Gething said he was "not sure" the prime minister would "announce their plans for Christmas tomorrow".
He said all four UK governments were due to continue talks later this week.
Mr Gething did not put a timetable on when an announcement could be made, saying the Welsh Government would "like to do it as soon as possible".
The UK Cabinet Office said ministers from the four nations agreed on the importance of allowing families and friends to meet "in a careful and limited way, while recognising that this will not be a normal festive period and the risks of transmission remain very real".
A statement also said ministers endorsed "a shared objective of facilitating some limited additional household bubbling for a small number of days".
Speaking to BBC Politics Wales, Mr Gething said Wales' First Minister Mark Drakeford "had another constructive conversation" with UK Cabinet Office Minister Michael Gove and other first ministers on Saturday.
Asked if an announcement could be made this week, he said: "We have a cabinet coming up this week. We'll want to consider the conversations and how far they've got over the weekend.
"We'll also want to consider the advice of our chief medical officer about the potential proposals for Christmas and to understand what that might mean in terms of the future health of the population but also the capacity of our National Health Service to help treat people and to keep them alive."
Newspaper reports suggest rules could be temporarily relaxed UK-wide over Christmas, with several families allowed to join one "bubble" and mix between 22 and 28 December, according to the Daily Telegraph.
Mr Gething said ministers were "looking at a timeframe that would allow people to travel" but would not be drawn on any detail.
He said he wanted a four nations approach "as far as possible to make it easier for people to understand what they can do, to help people to do the right thing".
Paul Davies, leader of the Conservatives in the Senedd, said: "It's good news for everyone that all four governments are currently committed to a four nation approach to Christmas and the festive season.
"Along with any potential vaccine, it is essential that the four governments work together to get us out of the pandemic united and together.
"People have family members and loved ones in all corners of the UK so having a joined up approach that allows people to get together no matter where they may live is vital," he added.
Plaid Cymru health spokesman Rhun ap Iorwerth has called for the government to think "compassionately" about which rules are in place between November and the new year, so people may have "at least one long bank holiday weekend with family".
"It can't be a normal Christmas, but I'd hope that everything possible is done to allow us to spend time safely with loved ones," he said.
Mr ap Iorwerth also called for a mass testing programme for areas of high transmission - such as the one in Merthyr Tydfil - and a "comprehensive vaccine plan" to be published.
On Friday, Mr Drakeford warned that if Covid cases rise, then people will not have extra Christmas freedoms.
Following encouraging news about coronavirus vaccines, with some successful trials reported, Mr Gething said it was "possible" the vaccination process could start before Christmas.
But, he added: "That still depends on whether the first vaccine, the Pfizer candidate, goes through all its regulatory and safety checks.
"If it is available before Christmas, we have a plan to be able to start vaccinating people this calendar year.
"To get population coverage, that depends on other vaccines becoming available, and we're not in control of that either.
"I wouldn't want to give a timeframe within which we'll have population coverage."
With Welsh Government officials considering mass testing all pupils and students, Mr Gething said he hoped to announce "over the next week or so" which sectors would be prioritised for rapid tests.