The 31-year-old rolled his ankle in round 16 against Carlton and missed the rest of the season. He had surgery in September and is one of a number of players facing later returns following off-season operations.
Craig Bolton, Adam Goodes and Tadhg Kennelly had groin operations while Luke Ablett and Ted Richards faced ankle surgery.
"Mick (O'Loughlin) is probably the longest one (to return) with his ankle operation," Roos said on Monday.
"Pretty much most of them will either be training flat out by January or running in January.
"There aren't too many a long way away and there is fair way to go before the start of the season.
"So six to 10 will start at varying stages. Some will start next week and varying stages between now and Christmas."
The Swans had 27 players at pre-season training on Monday including newcomer Rhyce Shaw, Nick Malceski, Martin Mattner, Kieren Jack and recently-crowned club champion Jarrad McVeigh. They faced a 3km run and a skills session at Lakeside.
Delisted Kristin Thornton has also been invited back to train with the club to help him regain some fitness after a wretched run of injuries.
Roos said he was expecting big things of Shaw, his new recruit from Collingwood.
"At this stage, he's in our 22 because we picked him up to play senior footy. Then at some point he's got to stand on his own two feet and get a game based on form and I'm confident he'll do that," Roos said.
Shaw, who played 94 games, was traded last month along with the Magpies' fourth round pick (No.61) in exchange for Sydney's third-round selection (46).
"He'll add pace and some outside run on that half-back line with Mal (Nick Malceski) and Marty (Mattner)," Roos said.
"The thing that Rhyce will understand here is that there real is a good balance between football and outside of football. But it's not until you're here for a few months until you fully realise that it's a pretty good lifestyle.
"But the main thing he needs to focus on and understand is his footy and training hard, which he'd have done at Collingwood."
