Can Gibber growth promoter be applied to very new grass, sown just a month ago?
Don’t do it. The Gibber will definitely damage grass that’s not well developed. It works by elongating cell growth, which produces more leaf mass. But the physical structure of the plant has to be strong enough to stand that kind of turbocharging effect, and new grass isn’t strong enough. It will elongate, then literally fall over because it’s not strong enough to support the extra mass, and will be ruined.
The label says don’t apply to pasture until it’s 12 months old. That could be a bit conservative; maybe 7-9 months would be OK if the grass is doing very well and you have tested a small area first to satisfy yourself that it wopn't damage the grass. But less than 6 months is definitely asking for big trouble I’m afraid. It will do far more harm than good.