Downing will be in the hot seat for Saturday's Premier League clash at home to Hull City, with Dean Kiely assisting.
The games come thick and fast after that, with the Baggies travelling to Spurs on Boxing Day and West Ham on 28 December, before Newcastle visit The Hawthorns on New Year's Day.
"I've not been given a specific time," said Downing. "It's been reported that I will be staying over the Christmas period, but it is a game-by-game basis. I am totally focussed on Hull.
"I will take it from there and if required over Christmas I will do that, but for now it's just Hull."
Downing has managerial experience of his own - albeit a short spell with Cheltenham six years ago - and says Clarke has told him to make sure he enjoys his time in charge.
"I have to embrace it, even if it is under different and sad circumstances," he added.
"I have spoken with Steve and he told me it is an opportunity to have a go at it. I managed at Cheltenham for 15-16 months and, even though it was a smaller club, it was still managing."
However, Downing admits he will take charge this weekend with a sense of regret.
"It's very sad and I had a huge amount of respect (for Clarke)," he said.
"I have learned from a very good man who has been in the game a long time and been under a lot of good managers.
"It's sad if anyone loses their job and there is a tinge of responsibility as I was part of the team.
"But he is an honourable man with integrity and he understood the decision. Now he has to forge a career elsewhere and he will do that.
"We have had a decent week and the players have responded well. We need to make sure we get the right result because three points changes everything."