The way we have always used it is prior to clipping and right before show. Sometimes in the hot months foams etc weigh the hair down. Zoom Bloom does give the hair a bit of a pop.
Man, it's been a day or two since we've use Zoom Bloom. It worked really well back in the day, we split it by 1/2 with White Lightning...and then Kleen Sheen later on.
Zoom Bloom is all we ever used for Show Day prep. You need to really spend some time blowing it into the hair. That part was always my Daughters' responsibility, but I would guess they spent at least 30 minutes blowing after they had combed in the ZB.