cuz like I just bought a 8 1/2 week old puppy so i was wondering how long it would take for him to learn his name

Depends what kind of dog it is, my dog took a while, about a month.

Dogs are very smart. After one month, the puppy should know you're talking to him/her.

It depends on how many times you say his name. i bet he will get used to it soon. if he responds to his name make sure you reward him with treats or praise him. they will enjoy it and respond to you.Frompippathecatt

i got an 8 1/2 week old puppy as well and by her official 2 month birthday she knew her name just repeating it a lot when you're holding her and petting her and taking her out. finish any command with her name. good luck!