new owner questions

I just brought home a 5 year old BP who is just the sweetest snake. I got her only 4 days ago and on the second day her belly started turning pink so i'm guessing she's starting to shed? I got a spray bottle and have sprayed lukewarm water in the tank a few times (she does not like it being sprayed on her. Learned that quickly.) I've left her alone to do her thing and i noticed today that she's spending a lot of time in her water bowl. She doesn't put her whole body in, just the 2 inches or so by her head. She stays in there for about an hour, then goes right back into her hide or stretches out and just chills. Should i be concerned about anything? I'm just a little worried because she doesn't try to put her whole body in, just that little area. I check the water to make sure there aren't any mites or anything, but i want to make sure there isn't another issue i just don't know about.

Also, the store said they fed her every 20 days but that's in a couple days so should i wait until after she sheds?

As long as you are not seeing any signs of mites, soaking is pretty typical around shedding. Just keep the humidity bumped up by misting her with a spray bottle. I usually mist once in the morning and once in the evening during the shed cycle and that seems to work. They don't like it but as long as you don't blast it, they are usually tolerant. I just spray mine lightly so the droplets are kind of falling on them and not hitting them.

As far as feeding you might as well way until after she sheds. However, I would feed an adult ball python more often then every 20 days. I would suggest for a snake between 1500 and 2000 grams that you feed at least a small rat once a week or a medium rat once every 10 days.