Santos was placed on the 15-day disabled list on April 21 with inflammation in his shoulder. He was recently re-evaluated by Dr. Lewis Yocum and received a clean bill of health to resume throwing.
On Tuesday, Santos threw for the first time since suffering the injury and is scheduled to go through a similar routine the following day.
"That will all be determined once we get off the mound," Blue Jays manager John Farrell said when asked if Santos would require a rehab assignment in the Florida State League before returning. "I would guess that's probably still two weeks away."
Santos, who was acquired from the White Sox during the offseason, has allowed five runs in five innings this season while recording two saves.