Unfortunately, I can’t do that in anim notify state, because in this the begin and end are functions. The only thing I can do is do the do once as you showed but inside the event call by the begin, or create a variable boolean to know if the ANS is executed (but I don’t like this solution…).
I think there is no other way than doing a do once on the event execute by ANS, and reset it as soon the swing should end.
Thank you a lot for your help and time !
EDIT : I think there is no way in the anim graph to disable the notify for a pose ?