How many meals do you let a hatchling pass up before considering assist feeding? Or do you?

I have 4 babies that hatched out last month. Started offering meals after first shed. I have offered 3 meals so far to all of them and they have all eaten except one. I have been offering meals once a week.

They are all on aspen in 6qt tubs with hides and I have been offering hopper mice.

How many would you let her pass up before doing something else?