Timing of staminate flowering.

[senorx12562]

pollen sacks don't just pop out and release. Females usually show first.

For females, you'll see one or two white hairs, like you'd see in a bud at the junction of the stem and a branch near the top of the plant. If growing from seed, I believe it takes at least a month after sprouting to show. They have to hit a certain chronological age, 12/12 or not.

there is a good example here with a pic of male preflowers
What are preflowers? - 420 Magazine

Thanks for the link. These plants were actually planted approx. 2 mos prior to flowering. In that time they never showed any differentiated sex parts, even though the branching went to alternating. Chronologically I think they are mature enough to flower. I decided to go ahead and put them in 12/12, in part because I needed the room in my veg room. I'd much rather lose them entirely than take any chances. We'll see.