Question about Masterminds synergy

DrAwkwardPhD

The Masterminds synergy, only a few champs have it. It gives you a 15% boost to your attack after a combo of 15. I’m wondering though, if I activate a multi hit special attack when the combo is at 14 hits, does the attack boost get applied at hit #15 or does it not count until the special animation is over, and not apply the attack boost because the input for the attack was prior to the combo threshold being reached?