Without knowing everything going on with the team (mostly the flu impacts) if the players are not responding to him real soon, I think SY will entertain making a change if there is no progress as a team.
This said, I think the best schedule windows to do it would be either at US Thanksgiving or around December 12, especially if there is a significant change in team philosophy, as there are some good practice windows and home game stretches' around these two time frames to work at the adjustments.
If not done by Christmas, SY might as well let him coach out the year and look hard at bringing up Dan Watson with the next wave of kids next season.
If the team comes together and makes a push for the post season (they are certainly not out of it yet), then Newsy may get extended for a year or two, but I think if Watson can snag a Calder this year or next with the Griffs, then he is in as coach as they send up more graduates.