Gah, don't use nix. It's NOT the same. Wait the 2 weeks until you get your next cheque and order PAM.
Long story short, there are inert ingredients in Nix (that manufacturers don't legally have to put on the label) that can be very harmful to snakes. You see/read about so many keepers who use the diluted Nix & haven't had issues, but don't play with fire. Their luck may run out one day when the Nix they buy doesn't contain the ingredients they think it does.
Trust me, I've dealt with mites once, and I know how badly you want to get rid of them. Soak the snake in a basin of warm water with a drop or 2 of gentle Dawn dish soap (to make a light layer of bubbles) for 30-45 mins every day or 2. Scrub the enclosure just as often. Take everything out except the water bowl and keep her on paper towel. This will eliminate a lot of them right off the bat.
Order PAM from the bean farm. It's produced AS a snake mite treatment, not a human lice treatment. Mine came within 3 days and the mites were gone with 1 spray down. I did a second treatment just to be sure. You don't need to worry about mites killing your snake but using Nix definitely wouldn't give you the same peace of mind.
P.S - Follow the directions on the PAM to the tee. Putting a snake back in the enclosure when it's not dry completely is a recipe for disaster. I usually sprayed my tubs & paper towel outside and let it sit out there to air dry for 1-2 hours until I couldn't smell any hint of the PAM.