I mean, if you just want to test the yeast, to taste the results and out of curiosity, I would try it when you can ferment fast, under pitch a lot and with a relatively light hop bill. Its really a kickass yeast and I've personally been using Voss for a long time, just harvesting new yeast when needed. The oldest yeast I've used was from a jar that I had In the fridge for a year! Full on krausen in about 6-8 hours. I mean, what's the point if you're gonna leave it for the same amount of time as any normal yeast