When do you think I should flower? NYCD and WW 4' grow space

So these two are doing excellent. One is NYCD and the other WW.
They're about 9"-10" right now and growing more every day.

My grow space only allows them to reach a height of about 4.5' max including the pot.

Do you think I should flower now or should I wait a bit longer?
I heard plants double to triple in height during flowering but that would mean my plants would only reach about 30" if I flowered now, right? Or am I missing something?

They're under a 250W MH and will switch to HPS for flowering.

Thanks for the help!

PS: First photo is NYCD (one photos), other two are WW (same plant, two photos).

I just realized that the WW has some female preflowers near the top. Does this mean I should flower or not necessarily?

Anything?

They're both 12" now; growing quite quickly..

Thanks

if your not topping,fimming,or going lst and I were in your shoes I'd start 12/12 now

I wouldn't flower untill yhere at least 1' 6".
Also I would top those girls so they can bush out a little. Otherwise looks like they are beautiful & healthy. You could flower right now if you wish but you will get alot more bud if you veg a little longer.