AsNoriuanswered grow question 4 years ago First round from day 14 till day 21 latest of flower.
Second at day 38-42.
Every strain is different , so that why you have to catch right moment.
On first wave bud has to be formed, not just preflower, never touch them tho
Second wave depends on maturity, check my Incredible sisters diary for more pictures.
By tactics you should trim all fully formed leaves till last FULLY formed one, even if its like 4th note from top, nit first or second. I recommend at least 50/50 lolitop together.
Do this before watering, and in plain water cycle.
I do trim in veg aswell, but normally try to harm them as late as possible, no stress tactics ;)