I'm not a parent, just a college cheer girl who struggles to juggle study, work and training.
Invest in a giant freezer and pre-make several meals when you have time. Lasagna, bolognese sauce, stews, pots of pesto, anything that's a meal by itself or only needs a few potatoes or some pasta quickly boiled up to make a full meal.
Homework in the car. Even if your cp isn't actually doing her homework, getting her to talk about the books she's reading for English, or what she's studying in history etc. really broadens her understanding of the subject matter.
Have a basket/bag of cheer gear in the car. A lot of my cheer clothes go straight into my big bag the minute I've finished laundry. If I forget that it's blue day at training, I've always got some sort of backup wear in my bag, spare shorts, socks, bows, etc. They may be the ugly ill-fitting shorts that I swore I would never wear again, but at least I'm in the right colour and have one less thing to worry about.
Have a glass of wine, watch some bad television and put your feet up. Taking some time for yourself now and then makes dealing with the cheer/work/study insanity a little easier ;)