The over drive was recomended to me by a good friend & was told to use it on the 3rd week in flowering then again right before the flush in the last 2 weeks . the bottle says to use just in the last weeks of flowering (weeks 5 or 6 ) . but he says the dose at week 3 helps the slower budding plants catch up .. could be bullshit but i have seen no problems using it in week 2 or 3 .