Plants can show sex within a few days of being put outside in fall. Mine all showed within 3-5 days. A week at most to be really sure.
What's weird is I have some on 18/6 showing preflowers pistils and they're only a month old. Though I have them outside for most of the day.
edit: woops I didn't know this thread was that old. Nice flowering plants.
I can't believe they're so big, WTF?
what kinda lights did you veg them under? Are they still only getting 4 hours light?
The buds look pretty big for only 3 weeks flowering... but I guess they ripen faster with less light