I'm not saying don't use it as I have never tried it, but I wouldn't use it on my first grow. There is so much that a new grower needs to learn, if nothing else, yu need to get to know the plant itself and throwing in another chemical this early in the game could be problematic.
Sometimes a plant can get a lil bigger than expected especially if you're growing hybs like I do and the BM will really help. Its not a chemical either but seaweed extract.
When do yu usually use it? I have some girls that have the tendency to grow straight up, even with topping, fimming, and supercropping. If I can't get a handle on them I might try that on the next grow cycle.