Reverend

I have this problem myself right now, so I've done a butt load or research. The bottom line is that the early stages of pre-flowering is too early to tell for sure if you have a male or female. I have, however, compiled the BEST graphics available (at least that I've found) to help all my peeps out there make the best judgement on the sex of their plants. Thanks to Old_Phart for a couple of these (from his link). The others, I can't remember where I found them, but props to the person who did them and supplied them.

Attached Thumbnails

     

 

__________________
"Never a dude like this one. He's got a plan to stick it to the man" - Superfly

Current growing disaster
My old GJ thread WITH PIX All Fluoro, Soil, Bagseed Grow (The new Thread with Pictures)
agent86's sweet-arsed germination guide (read for success, ignore for failure)
How to Tell Males vs Females
Want more females? Here's How...
When to Harvest

Reverend

I think as a follow-up point that it's important to note that until you either have:
a) white hairs; or
b) clusters of little balls

that it's too tough to tell. The little balls that are shown as male look pretty similar IMO to the sacks with white hairs coming out of them.

Time will tell!

__________________
"Never a dude like this one. He's got a plan to stick it to the man" - Superfly

Current growing disaster
My old GJ thread WITH PIX All Fluoro, Soil, Bagseed Grow (The new Thread with Pictures)
agent86's sweet-arsed germination guide (read for success, ignore for failure)
How to Tell Males vs Females
Want more females? Here's How...
When to Harvest