I would bud them depending on how hard they strech at the 12/12; when they get between 1 1/2--2 1/2 feet. i have 6 runs of personal experience using an aerojet 24 site in a 5x5x7 tent with a 25 gallon res, under 1k plus or minus a 400w; which is the precursor for the aeroflow. from my past 6 runs i've found that even when i had roots growing down through the drainage pipes and into the resivior that it def. effected the systems workability,without any positives to show for on the bud side, other then i hadda prune a hell of alot more. just keep in mind with those misters that any microbes you put in there are gonna make your root system and plants explode exponentially within 2 weeks, after their initial 1st week recovering from stress. so in short what i am saying is your gonna want to grow them like your use too as i did my 1st run (apprx. 2 1/2 to 3 ft when i flipped to 12/12) but you'll wind up making a huge hassle out of it. just remeber in hydro everything the roots need is constantly being given, so any changes to what your givin your roots in conjunction to your girls will be seen very very quickly there is no waiting around for microbes to digest nutes in hydro. the aeroflow and the aerojet are all about speedy runs with semi-compact plants and many a many slightly larger than popcorn sized buds; also somthing to consider i don't even run co2 in my hydro b/c the buds being produced are already big enough and high enough quality to meet my standards, for personal headstash no way! but for a 1 1/2-2 bow-a-run commercial Hell fuckin ya! Hope this helps ya out brotha and good luck on your 1st run with it, it's definatly a slight learning curve if your use to soil or soil organic. As always Take it easy :dance
BTW: i highly suggest going out and gettin a filter bag that you can put your pump inside of; even if your running all chem nutes i found that salts can build up if your not careful and will clog your precious little misters, which just turns into a huge pain in the ass. nd sorry for spelling i'm careless when it comes to that.