As a classroom teacher starting her 19th year, please, I beg you, instill the habit of DAILY bathing in your child, with soap. Hair should be washed every couple of days, depending on how dirty it looks.
I taught jr. high about 8 years ago and one of my classes was awful smelling. Just AWFUL! I finally broke down and had the "please shower daily" talk, if you need soap and shampoo, see me privately, etc., etc. I had one boy raise his hand and say (no, I'm not making this up), "I thought you only take baths on Saturday night before church on Sunday!" My, oh my, oh my.
I teach high school now and I STILL have foul smelling students. And it's not just boys (although they are the primary culprits), it's girls, too. Imagine how lovely class smells when young women choose not to bathe daily, it's their time of the month, they don't wear enough (or the correct) deodorant and their favorite outfit is low slung short shorts and tank tops. Very bad...
These habits are instilled in the early primary grades. Please, save yourself, your child and the school nurse an unpleasant chat/phone call and get into the habit now!