Suboxone contains buprenorphine
and naloxone. Since buprenorphine is an opioid itself, it will not precipitate withdrawal. So you do not need to wait any time for starting suboxone. Rather it will prevent the withdrawal symptoms
of heroin. The naloxone component does not work when taken orally and is added just to prevent intravenous abuse of buprenorphine by addicts. I think you probably confused suboxone with naltrexone
which can precipitate withdrawal. Taking meth can worsen your restlessness
in legs as all amphetamines
cause muscle twitching.
Since you have already managed to tolerate the worst part of heroin withdrawal, consider if it would not be better to completely quit opioids for good. If you are willing to quit, then do not start suboxone.
Hope this clears things up for you. Best wishes.