We start our hatchlings off on mouse hoppers, so your 3 month old can definitely eat them. We feed mostly live because we raise feeders, but I do keep some f/t rat pups on hand for when I run low on feeders (happens sometimes when we have a lot of hatchlings). When I feed f/t I just place the feeder in the tub and leave it...no zombie dance (I'm not good at getting them to eat with the zombie dance). So if your snake will take it that way that is great. Less work for you. I only feed f/t to the ones that will take it off the floor (or grab it before it hits the floor). Everyone else gets live.