I just re-read your question & realised I didn't give you a very clear answer. The three run throughs are your flush, done at one watering + the molasses water. All at the same time, just giving them a little time, few minutes, to drain between each run through. Then plain water as need till the end. Maybe using molasses one more time if they start to visibly swell again, no closer than a week before harvest (or as close as you can estimate). You actually have a better handle on this than you seem to think, so don't panic (you're not prone to anxiety, are you)? LOL!
-- Now you can sit back & contemplate your next grow. They were BIG, but is that how you like them (some people do), or would they be more manageable smaller? Now that you've seen how much they stretch in bud, you can time going into 12/12 at the right time to get the finish size you want.
-- (d00g, I hope you're reading this), I want you to google 'grow pot easy/mainlining'. What you get with this method is nice colas without the light fluffy sm popcorn buds. When done right, its doesn't cut down on yield, but concentrates the plants energies to the big solid colas. You can pinch as many times as you want to increase the number of solid buds, or as little (4 ) for fewer bigger buds. From there, you can go straight to 12/12, keeping them sm, or let them get as big as you want. D00g, this is what I wanted to point out to you. My flowering space is 5' X 2'. Not big at all. I'm still keeping my plants sm, going with only 4 branches/colas, but because this variety is a dense plant by nature, I wanted them open headed for light & air, which helps with bud health once they swell & start getting dense. This will work perfect in a small space without the room for a bigger fan (I'll only have space for a sm clip on fan, but good exhaust & intake). But check it out. Nugbuckets does a great tutorial & the pics are great. Very interesting even if your not into trying this technique. Have fun! Its almost party time!!!!