I can't remember exactly but I think it was about two months.
You don't have to put the whole plant into flowering to find out the sex. You can take a clone from the plant and root it under 12/12 light. When it's rooted it will show the flowers immediately.

Happy growing to you PPP
GTC21 Reviewed by GTC21 on . question to GTC21 just a quick question....how old were your afghani in the vegg stage when they started showing the preflowers....id love to know the sex of my plants but i dont wanna force flower then revert back to vegg to find out....happy growing and ty for replying to my post GTC.... PPP Rating: 5