I am the second owner of these. The first owner didn't wear them many times and I have worn them 10-15 times since I got them. They've never been washed or dried.
Waist (aligned): ~17.0in
Yeah, don't wash them. You paid a premium for the wash and the fit, so if you wash them you'll potentially lose both. I'm sure it sounds disgusting now, but just stop thinking about it and you'll be fine!