I know this is an old post but if anyone who isn't aware stumbles onto this post, do not, I repeat, DO NOT put yourself into pwd!
If you are on a long acting agonist like Methadone or Fentanyl then just wait. And my god do not do it on purpose!
You read about pwd on these recovery sites refer to it as "uncomfortable", that word dosent even begin to express the pure hell on Earth you will be in.
Imagine the worst wd you have ever been in. Now times that by 100. And imagine it all hitting you at once. It's pure and utter hell. I could sit here and describe my pwd experience in multiple pages and it still wouldn't do justice.
Please, do not take that Sub until all the full agonists are off your receptors and out of your system. There are conversion charts out there that can give you an idea of when it's safe. It's not worth it. And if you're going to a doctor to start a Subutex/Suboxone regimen, be completely honest about the last time you used and how much. It will save you in the long run.