I would say don't starve at all. Just try to introduce the new foods in unique ways. Maybe use some tongs or tweezers to wave the food in front of their face. Sometimes they need that moving action to hit something. If they decide they like the taste and will eat it, then just try dropping it in. If it floats (like freeze-dried krill) and is brightly colored, they are much more likely to take it than if it is something plain, like market shrimp, which sinks and is plain white.
I haven't had to starve any of my gar. A couple of them went 2-3 days without food, but it wasn't becuase I starved them, they were just too stubborn to eat what I provided. And I've had the best success with going straight from live feeders to freeze-dried krill. The orange color, and fact that it floats, makes it more likely to be taken than other prepared foods.