Just look for balls that look like itty-bitty grapes and look for white hairs (pistils)
Look here, this is from my first grow a while back.
That's a male in early development. They can develop a lot faster than females and you need to be able to differentiate between the two quickly as a male can ruin your crop quickly.
Good luck.
Anyway back to the banana stuff...I'm waiting on my seeds...I think Nirvana is messed up, I tried to email them and haven't gotten a response in 72 hours and I can't login to my account...WTF.
{mod note: no hookups allowed} ...PM me if you want.