Andre LeRoux special impulse

Andre LeRoux
[KoT:V/B2]
Cardtype: Vampire
Clan: Toreador
Group: 5
Capacity: 3
Discipline: aus
Camarilla: {If} a vampire you control would successfully bleed,
you can reduce the bleed amount by 1 to give Andre +2 bleed this turn.

When is corect impulse to use Andre text?
So i give scenario. Me vampire bleed,prey dont block,I have impulse to reduce bleed now,or I can wait to prey first reduce bleed or burn pool and then I have impulse to reduce?
We play online in (lackey) on second way,so prey get oportuniti ro reduce or burn pool,and after him burn pool,we say Andre text bleed reduced,is that corect(we play on this way many years,and nobody say how is that incorect)

It is similar to spying mission, i.e. after the action is successful but before burning the pool. That is later than most other reactions and modifiers.