I think going before you feel decent (energy, etc) during a lesson will just make for a rough, unenjoyable competition. Unless, of course, you thrive on the additional challenge of trying to perform well when you don't feel well (some people do).
It's one thing to wake up feeling a bit sick on a comp day, and to go through with it. It's something else to be feeling cruddy the week before, not having had regular lessons for weeks, knowing you're likely to still feel cruddy on comp day, and going through with it.
Take care of yourself. Future comps will be there when you are feeling back to normal!