Do not let soap and water run into the hole left from the feeding tube. It needs to heal from the inside out which can take a couple weeks. I would suggest showering with the peg site covered by a bandage for at least 3 or 4 days.
A drain sponge could be folded in half and in half again to make it a quarter of its regular size. Then cover it with paper tape and change it at least once a day after every shower. If paper tape doesnt work, try an ace bandage wrapped around your waist. Ive even heard of peg tube users wearing the stretch maternity bands.
Congrats and good luck