It only takes me like anywhere from 8-12 hours no matter what full agonist opioid I use before after using I can safely take sub with no precipitated withdrawls. I also have a super fast metabolism so that could be why it doesn't take very long. But in all honesty where ever your hearing that you need to wait a WEEK before switching from full agonist opioids like oxy or H to Subs is pure non-sense, don't listen to that its not true. AT THE VERY MOST wait like 48 hours to make the switch, and I highly doubt you would go into any kind of withdrawls, I mean even if you wait just 12-24 hrs you would most likely be ok, but if you are that worried about going into precipitated withdrawl from the sub than wait like 30-48 hours and go on it. I can tell you would rather do dope than go on sub, and if that's the case you may not stick to the subs and just keep doing oxy or dope but all it takes is a little willpower to make the switch. Like I said before, for that first few days to a week(more or less) after making the switch from full agonist opiates to bupe you may still crave oxy or H, but you wont be sick and its just going to be a mental thing at worst with the subs and that will most likely go away after switching from one to the other. And also I don't know which ROA you used for your subs before, but let me say that although your supposed to take subs under your tongue, that sublingual is the worst ROA, next to taking it orally to me and it only has like a 30% bioavailability I believe, or something like that very low. So for some people they don't think it works because they think you can only take sub sublingually since that's what the doctors say. NOT TRUE, sniffing and plugging bupe of any kind from suboxone to subutex(everything but the buprenorphine transdermal patches and buprenex which is liquid form of bupe made to IV or IM, I guess you could plug it maybe. though its rarely ever prescribed.) work very well, much better than sublingual does and so does IV too, but I highly advise not doing that.. REALLY don't do it! Plugging would be the safest and most effective method to take bupe(other than IV which isn't safe at all, but stronger), it lasts just as long as sublingual if not longer, and it works way better that way IME! Truly ask anyone who has tried bupe both ways will tell you plugging is way better and more efficient than sub'l. Sniffing isn't good for you and I don't really entirely recommend as it isn't as safe as plugging or sub'l, but if it will help you get off oxy or dope it is cheaper and safer(as far as ODing) to sniff bupe than any full agonist opiate your getting off the streets, and it also feels pretty good once you get used to it, but if you do this I would advise to get the pill form of suboxone in generic tabs, zubsolv, or subutex as they are much easier to do any ROA you want with. This is the only way I could make my self like bupe is by switching ROAs to different ones than sunlingual, by doing this I basically traded one addiction for another though at least with sniffing it, but its bupe and its safer than sniffing H that is for sure, plus I am legally prescribed it and don't have to worry about going out and copping shit everyday, so even if you do this your still better off than doing oxy or H. Try plugging it first though if you get back on it, and it will feel so much stronger than taking it under your tongue, also like I said I am not recommending you sniff it either as sniffing any pill is bad for you, just stating a fact that it works better that way. It sucks that the way bupe is meant to be taken is like the second worse ROA, sublingual, and the worst ROA is swallowing it whole or taking it orally BUT also I cant say this for sure works but I have heard swishing alcohol along with bupe under your tongue makes it like 2x stronger or something when taken sublingually so I guess you could try that too. In this order I will list the weakest to strongest ROA for bupe and this isn't my opinioin its a fact:
Orally
Sublingual
Sniffing
Plugging
IV