Hatchlings IMO need to be started on Mice whether live or pre killed. Its got a more natural smell to them over rats do. Once they establish a good feeding habit you can switch them easily to fuzzy rats or rat pups when needed.
I have female 1 month old would not eat anything for 28 days. Finally laid a pre killed fuzzy mouse in her hide with her and she ate it 3 hours later. So yes thier first meals DONT have to be live but it helps.
I personally after 10 days from hatching offer meals if they shed or not. 90% of them take it no problems. Its all on you if you want to wait or not most will eat for you if they haven't shed.