Personally ive done the same as i do with my fish over a period of no more than 30 minutes!
Thats put the bag into my tank, in order for the temperature to equalize, and then some of my water every ten minutes.
Ive done this with cherry shrimp, green singapore shrimp, black crystal and red crystal and every single one is fine!
I suppose it matters on the parameters of your water and that of the LFS, but provided your parameters are perfect i think they'd be fine!