I think it would depend on the fabric type. If its batiks ... no need to pre shrink..... but they run ....and run... so soaking them inthe sink( i don't think you want to pretreat with retayne for a swap???). Then just let them air dry on a rack, and press.
Other cottons i would soak in the sink as well, to saturate the fibers ( you may find a few that will run and can seperate them at this point). The heat from the dryer will pre shirink them but doing alot will be quite a mess. Use a laundry bag for delicates , it will keep them from being quite so tangled.
I would not pre wash Jelly roll strips of Homespuns ....way too much raveling... unless you want to overcast the raw edges prior.