I know, I'm coming in here late but I thought I'd share some thoughts of mine. Earlier on slow growth was a concern and you were in a dilemma over when you could clone and even topping or not, etc. Firstly, I suspect the initial slow growth due to an over-saturation of Nutrients. The soil mixture you described is quite plentiful and would substantiate a Full Vegetative Cycle depending on the maximum height wanted to achieve as long as the amount of its volume and size could keep up with the growth and root mass. Once you added Nutrients, the mix was too rich causing a "lock-up" and thus a matching reduction in growth as a defense to poisoning. Remember, this is a weed capable of surviving the harshest of conditions but messing with the "elements" causes a certain amount of risk and the plant will show you what's wrong. There are excellent posts here; sorry I don't have a link, but there's a guy who posted, about a month ago, a GREAT, well thought out and written post showing Nutrient overdose/deficiency and Pest problems with corresponding pictures. AWESOME READ!
I wouldn't worry about the ladies getting too big in their flowering lurch of growth. Isn't that the reason we grow? Rarely does a plant double in growth under artificial light. Again this is also strain dependent.
Topping is about the most severe thing you can do. A plant can only produce the genetically pre-determined maximum bud sites and topping only splits this. You cannot get more bud sites than the plant is pre-disposed to. Topping should only be utilized when height is a great concern, like in a closet/cabinet grow. By the way a suggestion: I always put a dab of roofing cement at the cut because the opening is usually as large as a pencil and invites disease and/or pest infiltration. Seals the hole, looks like shit, doesn't harm her at all and most of all, it seals her up good and tight.
I clone after I have Veg'd. my healthy, rooted cuttings about 3-4 weeks; looking for +/-18" tall with at least 4 nodes, preferably 6-7 nodes, again, strain dependent of course. I then let the pre-flower "mothers" settle back while flushing 3-4 days after taking the cuttings, for 2-3 days, then they go into the flowering room where they switch over to the infamous 11/13, on/off cycle of HPS. I end up with a plant that is close to 24" when entering flowering. This way I don't have to keep "mothers", saving valuable space and more responsibility. It does require me to be at least 80% successful with cloning. Got it covered.
The maximum potential amount of bud sites, the potency, the overall genetics are exactly a result of that. Given the best environment, with each and every factor of growing covered p-e-r-f-e-c-t-l-y, absolutely 100% done to perfection from beginning to harvest, the outcome has a genetically pre-determined, maximum potential that the plant will produce. What we are attempting to do, is to get as much of these factors addressed and to the best that we are capable of fulfilling in producing these specifically...
Best of luck to you. Looks like you got another 4 weeks? or is this strain faster? Hope it's great!