You can veg 0 days with the clones, I am reasonably certain, at least with some strains. In other words, put clones in little pot, and flower immediately, the same day. I've tried two SOG experiments now, using Nirvana AK-48. The first time I gave them 5 days after potting them, and they're 3.5 feet tall now at day 48 of flowering, even though they were at most 5" tall to start. The second time I gave them a mere 2 days after potting them, and those plants are 31" tall now, not counting the pot, at day 28 of flowering, even though they were like 3" or 4" tall to start and had had only two days to spread their roots before flowering. Freakin' amazing how big they have gotten considering how tiny they were to start.

You're going to have to experiment to find the right point for your height limitations and the strains you are working with. If you are severely height-constrained, I'd suggest flowering them immediately the first time, and work your way up from there if necessary with future crops. If height's not an issue, then it doesn't matter much I guess.