My first book got approved!!!
I'm excited.

Oh, and I got a doubt, is it necessary to upload a chapter every day ?
I think of doing weekly every Friday.

Congrats!  
No, it's not necessary to upload every day. Upload as often as you feel is comfortable for you. Being consistent is the key to getting followers. Every Friday sounds like a great schedule!
Hope it does well!

Welcome, my first piece of advice would be to look for the "How to respond to criticism" guide in the respective guide thread. It's very crucial and important for your mental health if you aren't used to putting out your creations to know how and when to take criticism. I'm sure you'll have a good experience but it never hurts to know just in case. 

Also again, WELCOME TO HELL!

Congratulations and welcome! Hope you enjoy your time here.

As for uploading schedule, I don't think it's that important as long as you are consistent. It might slow the growth of your story a bit though.

That's very exciting. Congratulations. As everyone else has said, consistency is the key. Once a week is a fairing common release schedule here. You might check in the Art section of the Forums to see if anyone's currently offering to do covers. They're not required, but are helpful in drawing readers.

Ohhh so exciting!! I hope you enjoy writing here!