New Grower critical mass auto

[green1]

hi all i was told you couldnt top auto plants or super crop but iv read on hear people do wen would be the best time to top or super crop an auto plant. mine are critical mass auto and just been potted in normal multi purpose soil as iv never had any problems with it and they are in 7 inch pots under 125 cfl blue spec then will be going under 600 hps any ideas.thanks all.