Avoiding the time release mixes helps at this point. During a normal MG grow, the pellets have dissipated and are of no further consequence. If you do continue with the MG, no flower nutes for at least a week or so, then start half-strength and watch for reaction. (you aren't filling a whole pot with fresh MG, you're just adding soil around the existing rootball)

I'd keep the same schedule, but with the understanding that it will stretch more than usual before starting to fill-in. With what I use now, I usually transplant into it's final pot after a week or two into flower.

The only exception is if I'm using the MG. With MG I'll transplant a week or two before switching, so most of the nutrients are depleted when I do switch to 12/12. A mature plant will eat-up the nutrients quicker than a young plant, so the nutes don't last as long. There will still be residual, as it is a slow dissolving pellet...but really does no harm.