I've offered before and after first shed. As long as the umbilical area is totally sealed I see no problem before shed. It's not like they will pass a meal by in the wild.....
Little hatchling thinking.... "I have to pass on the little rat pink cause I haven't shed yet" .... lol!!
Both my Black Pastel Pieds shed yesterday and took rat pinks. Love starting out of the gate with rats!!
Only exceptions are for the exceptions such as hatchlings that do not shed within 2 weeks of hatching, hatchling not absorbing their yolk etc. Those are rare and feeding is done on a case by case basis.