it hard to say I started force feeding/assist feeding my one htchlnig ( non boob egg) once she lost about 1/3 of her total hatching weight. inyour case I say I be more inclinde to force feed once it lost about 1/4 or about 5 grams being snake the little guy won't have much fat or stored energy. I also start with a smaller preay maybe a fuzzy mouse or so ( don't want to force too large a prey into it. )

With mine I had to do it about 3 times then she just went nuts and tried to eat everything that moved in her tub ( including fingers and my nose when I was checking on her one time holding up to the lightosee her better lol..