First I ain't a Dr.. Big D boy has explained it well. H is not a long acting opiate the issue is more receptor coverage as I understand it, both the bup and the nax knock the H from the receptors and the bup replaces the H. If you don't have enough bup. to replace the H you will experience the prec. WDs, it has also do with you total length of use because your body over time produces more receptors hence tolerance to H or nicotine or whatever. Also how you introduce the sub. a lot of Dr.s will do induction in there office to make sure that your dose get all the receptors covered. So if your doing 4-5 bags of H and the Dr. gave you a 2mg pill to take for induction it doesn't matter how long you wait your not going to stop the H WDs. Also if methadone is mixed in at all I hear thats almost impossible to make the transition because it is a sticky op..
What were your induction instructions besides follow the cows. Dosage and such? Like I said I'm not a doc just speaking anecdotally.