Been a few years since I was there too, 10 years.
Time of year would depend on your ability/route choice and general snow conditions from the prevailing winter.
Possible best times of year for popular routes:
South Face, technical,steep. Best tackled in winter or early spring as good freezes are important.
South west ridge, awesome route moderately steep through couloir. winter possible up to early mid summer. Ice/snow accumulation needs to be good through couloir otherwise its a miserable few moves on dodgy rock.
Northwest ridge via ramp, good all year except winter avalanche risk and late summer the entry to ramp can be tricky or cut off.
Northwest ridge via shipowner ridge. Good option for summer, late season it can be a rock scramble from colin todd hut all the way to summit snow slopes. (seen guys in trail shoes on this)
Other consideration is fitness, very rewarding to walk from car park to french ridge hut summit via SW ridge and back out. Lazy option (and best for getting a weather window) is to organise Charlie Ewing in the valley (still around?) and chopper to bevan col.
its an awesome peak, work out a weather strategy, i.e walk in with crippling sized packs to a hut or hang out in Wanaka and wait for the window and chopper in. I know what I would do nowadays ! enjoy. for Mt aspiring guide books contact NZAC.