I trim through veg. and flowering ... just dont trim too much on the same plant - and give them some recovery time before trimming anymore . I always did any major trimming in small increments .... was always afraid of stressing them too much wich can lead to hermies.......
i trim up 6 inches or so from the bottom in veg so the plants dont waste energy trying to produce all the little bullshit nugs that never get light in the bottom and just piss you off whenr trimming