You should judge when to flip them by the available space you have & how much training you plan to give them as opposed to how much weed you want to harvest. With a 1k light you could get more than a qp per plant but your tent sounds a bit narrow in depth which means it'll be real hot in there. Be sure you've got a ducted exhaust fan or you are gonna have heat issues.
Personally I like to flower out in 7 or 10g pots & usually harvest 3-5 oz per plant depending upon strain & conditions. There are 2 schools in veg time: more plants;less veg or more veg time; less plant count. Obviously you can fit a lot more 3G pots than you can 7g pots but you will pull much more bud off the plants in 7s yet wait longer in veg phase. I think a longer veg, I try to go 7-10 weeks for clones & maybe longer with plants from seed but my early veg cabinets run on cfls which promote slow growth. I top each plant several times, tie down the tallest branches to even out the canopy, LST the living shit out of them, supercrop all the tallest nodes, and bend every internode I can get my fingers on to even out the canopy & expose as much nodal area as possible to the lights.
A good rule of thumb is 2/3...when your plants are 2/3 as large as you want then flip to 12/12...they will grow another 30% during bloom. The key is to veg until your plant is as large as it can be while still allowing you're lights to penetrate into the canopy. If you keep the canopy as even as possible through training or a scrog net all the bud will be the same uniform size. Untrained plants will grow a single bud on top which is fine for a sog- faster turnaround but a golf ball sized bud at each cola. It's possible to overveg because your 1k will only penetrate so deep: the only viable buds will be at the top 9-12 inches of the branches & the rest will be good for making hash or edibles. So that being said allow your plants to fill in the tent with as many nodal sites that form buds as possible, keep the canopy as even as possible, and spread those colas out to allow light to the lower nodes & you'll maximize yields.