I generally let the starters go for about 12-24 hours on a stir plate. I use the same method/timing whether starting from washed yeast or wyeast packs.
Atomic Dog Brewery
On Deck: Centennial IPA, Dry Irish Stout
P: Cascade Pale Ale
T: Carbed Crystal Light, Root Beer, Vanilla Cream Soda, Tripel IPA, Apfelwein
e^(pi*i) + 1 = 0