Bf had stomach virus on 12/26/2019, he threw up only that day but was symptom free on 12/29/2019. when is a good time to see him again? & have physical contact with him (kissing, hugging, holding hands, etc.) w/o fear of him still being contagious?

Usually safe at 4-5d: Contagiousness varies among different "stomach viruses" and among different people, so is not easily predictable. However, one can feel safer if the sick person wakes up on Day 5 without any symptoms the preceding 4 days. If unlucky, she can still catch a virus and come down with the illness. Food poisoning is usually less contagious, but depends on the bacteria type.