When should I flower? 10 plants 1000 watt light

I have 10 feminized plants, all with pretty healthy growth. All organic soil grow, I'm just unsure when I should flower. They were all been transplanted into 3 gallon pots about 2 weeks ago. Height ranges between 6 and 9 inches. Space is not an issue, 10 by 13 ft room. The only real limiting factor is the 1,000 watt light.

I was thinking at about 1 foot i should flower? I've never grown this many plants at once, thank you for help +rep

you should almost start flower now, wait how big is your hood?