I just noticed a few blisters on my one year olds feet ... he had hfm in august so im almost positive he has it again .. when should i sanitize my hom?

Not your fault: Since there are several viruses which might cause hand-foot-mouth disease, a child might get it more than once until there is immunity to all of them. A vaccine against 1 or more of them may appear in the future, but there is no protection presently. Exposure at some time is inevitable no matter what you do. Avoid unnecessary antibiotics.