when to switch veg/flower, and when to trim bottom 1/3

this is my first indoor grow. I'm running 600w is a 5x5 tent. Three plants are criptic kush, and one is bay dream. All in soil. They're ranging from 6 to 8 inches and I've had them going 2 weeks (got them as clones).
I've heard some conflicting opinion on when to switch to 12/12. I've heard 12", 18", when you feel like they're ready, etc. Is there any best answer to this question?
Also, as far as trimming up the bottom 1/3 of the plants, how early can i start that? I've only done one outdoor grow (hell of a learning experience) and I didn't trim up the bottoms of those till they were a foot and a half tall. They were super thick, but man they loved it when i thinned them down. So.... how early is too early to start cleaning em up?

It depends on your grow height. Most plants stretch 2-3x flower size. So plan accordingly. You can cut the bottom 1/3 as far as two weeks into flower. Take some off the first week and clean up the 2nd week.

adower said:

You can cut the bottom 1/3 as far as two weeks into flower. Take some off the first week and clean up the 2nd week.

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Are you saying i should wait till the first and second week of flowering to clean up the bottom 1/3? I was hoping to take some of that out so they would spend more energy growing up and out, and less energy on all the crazy underbrush.

Im also interested in this as im in a similar situation (5x5 tent, 1000watt MH, 9 plants) and its starting to look like its gonna get pretty crowded and im only in week 44 veg, anybody have a trimming guide for shorter, bushier indicas?

i manicure even up till near the end. but if there's triches i don't waste em. i kief them out. if your plants are getting too tall just tie them bitches down. bend the stems. in veg and early flower it'll induce more bud sites.

If your concerned with height before your into flowering Top her and or mix with LST your bush will become many ..... gl also Iv heard no topping in flower, Im only on first grow and doing this but my plant looks like 4-5 in one pot and it will increase your yield severely

p.s Id guess give the plant a good 7 days for recovery and the 2 new tops (plus the new tops forming at stem and branch meets will also form tops) to come in and be growing nice, not sure youd be advised to do this in flowering stage though. Gl

I would avoid doing any major pruning during flowering. It will stress the plant and slow it down some, or worse it could hermie. You can clean up the lower shoots anytime.
If you do trim it earlier you will probably want to trim it again about a week before you put it in flower. Then if/when you clean it up again in flower there will be very little stress on the plant.