Mail order plants

What is a reasonable time to wait after arrival of Mail order veggie plants to be planted out? I'm trying to write the instructions on how to care for plants once they arrive. I have clients that have completely ignored my instructions then expect me to make good. What is a reasonable length of time to let the plants recover from shipping and acclimate to their new environment? Example: client wants plants shipped on 5-2-11 so they can plant out on Mother's day, which would be the coming weekend. That doesn't seem like enough time to me.
Thanks

Are they actively growing when you package them? How are they packaged? My thought would be the sooner the better for something like tomatoes (if the weather is warm enough,) 2-3 days for cabbage and such.

Shipping can be very stressful for plants and while they may be hardened off for my area they need to be hardened off for their new home.