Question on my new generation (2)

I have a question, my first grow, margarit who is about a week away from harvest was my only plant i was lucky and she turned out to be a she. My newest plants are at about the 5-7th growth node and i was wondering when is the earliest time you can get your plants to show sex... some of the larger plants side branches are getting life.

Well, if you want to flower, just switch your lights to 12/12. You'll see signs of sex in about a week. If you dont want to flower right now, wait until after their 4th week of veg. This is when a lot of plants start to show preflowers.

i know that around a month old or so you can start plants into flowering but what i was wondering where would an example all indica or all sativa plant be with accordance to height and growth nodes my tallest indica is now about 7-8 inches tall with its 7th and 8th growth nodes just opening now. i want to first just sex my plants and then bring them back to veg so i wanted to know the earliest size would be effective in sexing them. Thx... Btw last week on my first plant "margarit" who is looking sexy but rather petite. for the next grow i am looking in to buying a bigger light. right now just lots of small cfls and 2 poorly placed (far from plant) 100 watt HPS flood lights... pics from last week...

anyone have any two cents?