max motoring
You raise the start lever at 25% and there is no need to wait for more. Captains who do this are breaching SOPs. and indulging in personalised techniques. Max motoring means more than 20% (below that you may get a hot/hung start) and that the engine has stopped accelerating towards 25%. So, this condition will be between 20-25% N2.
on the -800 this hardly ever occurs due to a powerful APU but on the -300 it was quite common and you would put in the fuel at maybe 23% due to having reached "max motoring".
Yanrair