It all depends on how much time you have, wet food has to be changed daily, dry food you can keep some out for a week or so, just check the food on a regular basis.
I use dry food since my free time is not that great, I usually get maybe 4hrs at most eachday when I don't have something to do, and that goes to writing and caring for Sonic... Do you have a wheel, as well as a scale.
There is no guidelines on telling if your hedgehog is fat, other than seeing if he/she can roll into a ball, you have to check the weight sometimes, I weigh Sonic once a week. If its a steady weight gain its ok, since it means he/she is growing. Keep in mind that if your hedgehog uses the wheel a lot you are gonna have a heavy hedgehog since muscle weights more than fat!