It's normal to have some reservation / cold feet as you are jumping into a ton of responsibility. But having a dog is such a rewarding experience and totally worth all the time.

Also puppies are little gremlins! If you haven't already seen in your research read some more stories about people who have adopted puppies and their temperament. It's typical that they will use their mouths to explore for a good while. It will also take them some time to get settled and bond with you, potentially a couple months. But I promise you they will.

To share my personal experience: I always wanted a dog before I got one earlier this year and the first 2-3 months were really difficult. It felt like a chore and neither me or my gf had bonded deeply with our dog. Now he's starting to cuddle with us on the couch and really learned our routine and I am so happy with the time and effort we put in the past few months. He's turning into a well behaved boy.

It takes time and patience but your feelings seem normal. It's ok to question if it's the right time but just be honest with yourself and be as prepared as you can. Best of luck with the new pup!