I prewash everything except for precuts as soon as the fabric comes home. I do it to remove chemicals, to pre-shrink, and of course to try to stem bleeding. I wash in warm, dry on hot, then fold it right out of the dryer. I don't iron or starch until I'm getting ready to do cutting since there are folds to iron out no matter what. Sometimes I use Retayne if it's a fabric I think is going to bleed a lot.
All that work is a pain but I think I get better results that way. Plus the idea of having to wash and fold all the fabric in my cart as soon as I get home has helped me decide NOT to buy quite as much fabric sometimes and I count that as a good thing!
It's interesting though - it seems like some fabrics RECEIVE bleeds more than others. I've washed reds and whites together in the past and had no bleeding anywhere except ONE of the white fabrics came out pale pink. No blotches, no bleeds on any other fabric...just the one with a surprisingly uniform pale pink. Very strange! I know it wasn't pink going in there!!