when can i tell the sex

Im using florescent lights to grow until ill be able to afford a hps light but i switched the plants over to 12/12 a week ago and i was wondering when i should be able to start to tell the sex, there is nothing showing yet at the internodes.

i could be wrong but im pretty sure its 2weeks into flowering don't go by my answer though get more input.

i think its about 2 weeks plus into flowering

I'm sure it's strain dependent, I had all six of min sexed at 6 days and the single male showed at 4 days. Thes were plants that grew from seed and were 45 days old when they went to flower.

Male 4 days after switch to 12/12: