halo use before grapplers quest

a buddy of mine is going to compete in grapplers quest in September. he was asking me what he could take that would get him stronger yet not put any weight on(he's going to be cutting to under 199lbs). i said halo is probably his best bet considering it has no anabolic properties. he want's to take it but is rather cheap(and is concerned about his liver)so he wanted to know if he could take it just a few days leading up to the competition or does he have to take it 3-4weeks before leading up to it. anyone know if he could just take it a few hours before hand for it to give him the extar kick he's looking for?(i'm sure he'll take it to experiment a lil with it when he rolls in practice too)