However, the FCOM DSC APU is pretty clear about it:
Avail: this green light comes on when N is above 95% or 2 sec after N reaches 95%.
The APU may now supply bleed air & electrical pwr.
It doesn't leave any ambiguity.
Maybe you would prefer to wait 1 extra minute.
But if we follow your reasoning, then another person would say no, let's wait 2.5 minutes and a third one would say 2 minutes in fine.
What's wrong with doing something the standard way??
If Airbus would like you to wait, don't worry they'll tell or advise you.
Last edited by Feather44; 14th Mar 2017 at 18:04.