too small to flower?

I'm growing a few plants and I was wondering if they are still too small to start on their flowering cycle? They are all about 12-13 inches tall and the strains I chose do not bush out much. My roomate is kinda freaking out because his daughter is going to be moving in with us for school this year and he would like me to have them done b4 she gets here or at least shortly after. They are about 2 - 2 1/2 months old and have had preflowers on them since they were about 4" tall, even under 24 hrs of light. Are they big enuff or old enuff to start them flowering?

Also, since my next grow will also be in a 2.5 ft x 4.5 ft closet, I was wondering if any of y'all could recommend a few strains that would do well. I prefer a nice indica/sativa cross since i dont want a purely cerebral thinkers buzz, nor do I want wheelchair weed. I have heard some of the crosses yield a euphoric, trippy buzz. Someone suggested white rhino. Any ideas?

You can flower anytime. When growing from seed, your plants are mature when they start showing preflowers.

Good Luck