Foster has been sidelined with a calf strain since the 2-1 defeat to Hearts at Ibrox in the opening league game of the season.
The defender had hoped to be fit to play for Ally McCoist's side against Queen of the South at Ibrox tomorrow.
However, the former Aberdeen and Bristol City man is now looking to make his comeback in the meeting with Raith at Stark's Park.
Rangers will have a 12-day break from competitive action after the game with the Doonhamers due to their Petrofac Training Cup quarter-final with East Fife being postponed.
And the 29-year-old is keen to be back in the starting line-up for the trip to the Ramsdens Cup winners in Fife.
"Progress has been slow and I don't want to rush and end up being out for longer, but I think that I should be back running on Monday," he said.
"I'll do a week of fitness from there then hopefully I'll be back with the team challenging for a place.
"Just now walking about on it I don't really feel it. I've been doing quite a bit of work on it with the physio.
"It's only when I go outside and try to properly load it that it could flare up again, so we're just taking our time and making sure that it's right."
Foster, who has been replaced in the side by centre-half Darren McGregor, admitted he has been frustrated to be out of the Rangers first team.
But he has been pleased to see Rangers record consecutive victories over Falkirk, Clyde, Dumbarton and Queen's Park in their last four matches.
He said: "Thankfully the team are getting into winning ways and that builds momentum and that's all that I want.
"Obviously I'd much rather be playing, but as it stands I can't so it's nice to see the team doing well.
"It's going to be a really tough game at the weekend, but after that there is a bit of time for me to get fit which has maybe come at a good time for me.
"Hopefully by the time the next game comes round I'll be fully fit and in contention."
While Foster has watched on from the sidelines in recent weeks, one man in particular has caught his eye.
Lewis Macleod has shone for the Light Blues so far this term, his fine form rewarded this week with a call-up to the Scotland Under-21 squad.
And Foster is confident the midfielder has a bright future in the game.
"It's only early doors, but Lewis has probably been our best player this season so far," he told rangers.co.uk
"I've loved to watch him - he's quality on the ball, his movement is fantastic, he has a great range of passing and a real ability to get goals.
"He's arguably one of the best young players that I've ever had the pleasure of playing with.
"When you've got the football quality that Lewis has, it comes back to you very quickly once you've been out.
"We've seen it from pre-season and the early games this season the natural ability that he has. We've seen already from this season that if he can keep going he'll be a top player."