My friend recently had the flu. how long should i wait before allowing him to be around my 4 month old daughter?

Caution: You ask a very good question. I would say at least 2-3 days after being fever free. Of course it goes without saying friend should not handle child while active symptoms and should use common sense hygiene by washing hands before handling child

Minimum 7 days: I consider anyone with flu to be contagious for at least 7 days from the first fever whether it stopped on day 2 or not. Oftentimes the treatment with Tamiflu will suppress the fever, but they can still spread the germ through their saliva or cough for a minimum of a week.