When to use liquid Budswel

I'm gonna be running a hydro op that goes, from clone straight to flower (Al B Fuct's perpetual lollipop technique) and was wondering when to use Budswell. Should I use the entire time or just the last couple of weeks? Thanks in advance...

Anything? I'm gonna be heading out to pick some of this stuff up tomorrow and I'm hoping for an answer before I go.

I'd much rather hear what you guys have to say than the guy at the store who may just be trying to sell me stuff.