Well if it's compared to the 1% return you get a year keeping your money in the bank I would say waiting any amount of time for a 1,000+ % gain is worth it.
"So how long is too long to wait?"
I have waited days and I have waited years before when playing micro float / micro market cap plays like this one and every time the wait was well worth it.
I think ATMH dose not have much more of a wait. Most of the waiting has been done already. Now would be the best time to load. IMHO