cash crop, 3 weeks old

Hello, I'm growing a cash crop strain from Cream of the cro. It's 3 weeks old and growing lots, I have 3 40 watt cfls on it right now and when it starts to flower I'm going to put 3 more 2700k 40 watt cfls on it. Should that be enuf to flower it?...... also it's growing fast and only has about 3.5 to 4 foot high grow room. What if it grows to big???

Recommend you do some reading, or prepare for unexpected results. If you're sticking with CFLs the whole grow, you don't want to wait much longer, if at all, in terms of vegetative growth. You will not have the light intensity required to grow a large plant with just a handful of of CFLs. Assuming this is a first grow, consider also that you need to keep those lights close as well (a few inches from the plant), spread them out, and keep her from stretching into the lights and wilting leaves. You girl looks nice and healthy though. Good luck, whatever you do. There are a number of factors that can influence the stretch (rapid growth at the onset of flowering), but if you flower sooner than later, you can minimize your risk of it growing out of your available space, which I don't see it doing unless you keep your lights up high.
Look into something like this for more information and tips: http://www.amazon.com/Marijuana-Horticulture-Outdoor-Medical-Growers/dp/187882323X/ref=sr_1_1?ie=UTF8&qid=1419143877&sr=8-1&keywords=jorge+cervantes+growers+bible

I downloaded that book for free from TPB, before the site went down a while ago. I'm sure you will be able to find torrent links on other sites too though..... I'll have a quick looksee shortly and iif I find any, I'll post the links here.

EDIT: As promised... http://kickass.so/marijuana-horticulture-the-indoor-outdoor-medical-growers-bible-pdf-gooner-t8496946.html

Thanks for the replys, I forgot to mention she is an autoflower so I have no choice but to let her grow a couple more weeks. The only reason I haven't put those light inches away yet is because it seems to be vegging pretty well as is and I don't want it to veg to big before it flowers. Once it starts to flower tho I'm gna have 240 watts of cfl as close to her as I can get it. Cfls are my only option for the space and budget I have but I got a pretty bright box and I'm hoping I can make it work. I'll post another pic at 4 weeks to judge the growth

If it was my garden I would top it very soon once and begin super cropping or your canopy will be unmanageable for your grow space.

Autos aren't good at taking topping they have a limited life span.

I've heard topping ,it and any kind or pruning really, is not good for autoflowers.... but if I was to top and/or super crop it how would that even help?

Topping restructures the plant to provide multiple top colas, requires extra growth/recovery time but can put a little extra "developed" bud on the table. Not good for auto-flower strains though, as has already been stated.