Your Pacman is a few months younger than mine and I feed her every 2-3 days. If you want to beef him up a little more (since he hasn't been eating) you can try to feed him more frequently than that.

You'll find a lot of different opinions about how to feed your frog, and honestly whatever works best for him is probably the way to go about it. Remember my friend who couldn't get her baby frog to eat? It's because he didn't like to eat food at all unless taken out of his tank, put into a separate container, and having it offered to him on tongs. I'm not sure if he's still so picky, but depending on their little personalities and how they were raised, one frog may prefer to eat one way vs. another.

Another factor to consider is if there's anything he can accidentally ingest in his enclosure (like sphagnum moss) and if it would be safer to feed elsewhere.