Donnatal (belladonna alkaloids/phenobarbital) 1-2 tablets every 4-6 hours as needed, maximum 8 tablets/day
For overall reduction in withdrawal symptoms including anxiety, restlessness/agitation, insomnia, tachycardia, hypertension, andm uscle aches and pains.
Catapres (clonidine) 0.1-0.2 mg every 4-6 hours as needed, maximum 0.8 mg/day
For insomnia
Ambien (zolpidem) 10 mg at night as needed
Lunesta (eszopiclone) 3 mg at night as needed
Restoril (temazepam) 15-30 mg at night as needed
Desyrel (trazodone) 50-150 mg at night as needed
For anxiety, restlessness/agitation, insomnia, and nausea/vomiting
Thorazine, Largactil (chlorpromazine) 10-25 mg every 4-6 hours as needed
Stelazine (trifluoperazine) 1-2 mg every 12 hours as needed
For anxiety, restlessness/agitation, and insomnia
Seroquel (quetiapine) 25-50 mg every 6-8 hours as needed (100 mg at night as needed)
Zyprexa (olanzapine) 5-10 mg daily as needed
Buprenorphine, the opioid in Suboxone, has a half-life of 20-44 hours so it will last a long time. I can't and won't advocate or recommend you return to using Heroin or any other opioids (especially IV use) but I will tell you that you probably need to wait more than 36 hours. 72 hours could potentially be long enough but longer may be needed. Also (and I am only telling you this so that you can do things more safely) if you do start using opioids illegally/improperly don't start with IV use. If you inject a drug like Heroin and the Suboxone is still exerting an effect it will precipitate a very severe withdrawal. If you took Heroin orally you will have fewer risks. And when it comes to drugs don't assume you have a fast metabolism- it may be that you do but it is not something you can easily tell (even if you think you can).
Lastly your question asks "how long do I have to wait (with a pretty fast metabolism) before I can feel the affects of the H or another opiate?" From that it sounds like you want to go back to Heroin to get high and your concern is mostly about getting high rather than trying to just prevent withdrawal symptoms and try to stop opioids.
In any case talk to your doctor see what can be done to keep you off Heroin or other opioids. Make sure your doctor knows about your financial issues and the fact you are wanting to start using Heroin again.