Hello Abraham! Not sure I'm reading your post right. You say want to raise 3-5 Grey Tree frogs from tads. Then you ask if you should do that, or wait for the froglets to emerge from pool. Guess as long as it's legal, it's your choice.

If you want to observe and care for the tadpoles and have the aquarium set-up required for that, it's OK. Also, if your family is going to put the pool in service; then moving them to a kiddie pool with water from where they are would be nice too.