Northern leopard frogs (Rana pipiens) take around 9 days to hatch and most transfom into froglets in 4-5 months though some overwinter, don't expect legs until at least the third month, keep in an unheated aquarium and feed the tadpoles algae wafers, hair algae, goldfish flakes, and koi kookies, areate the tank with a sponge filter or airstones and try to do 30% weekly water changes with dechlored water.