The fuzzies are better, but not quite as good as a small mouse.
As Rich said, the more mature the animal you can give, the better.
Having said that, its best practices, but not the end of the world. For example, I switched my carpet python from mice to rat pups early, because they can imprint on food and better to get him switched than worry about feeding multiple mice.
They survive in nature on whatever they can find.
Still, if you want what's best, go to rat fuzzies if your BI can handle them, or try to find some mice in the meantime.
Remember, less is more with boas. Not too large a meal and not too often either. As your BI gets older, you will want to start spacing out the meals more.
Also, no dumb questions here. Keep asking and learning. Good you want what's best for your BI.