BTW, forgot to ask, were you on methadone just for pain? Curious because I've been using subs for pain as well as dependence myself.
I don't have experience with methadone but I know that subs have a 36 hour half life but whether you can use other meds depends on your dose. Using a very small amount of subutex, I can take a couple pain pills as soon as 24 hours later and feel some effect. The longer you wait the better but some people also say that stacking a full opioid (like percocet) on top of a partial (like methadone) CAN give a pain-relieving effect although you won't experience euphoria.
If you have a large supply of percs, I'd say give it a try as soon as you can feel the methadone waning. If you have a fairly limited supply, I'd say wait as long as possible. Methadone will increase your tolerance a lot (what a bummer as it doesn't feel as good, right?) so you will probably need more percocet than usual at first and have to taper down a bit. I would think the longer you wait for that first dose, the better chance you have of keeping it low.
Methadone has a 36hour 1/2 life so about 3 days you should be ok on the switch perks are a lot ezer to detox off of then methadone...Gnarly