First time mom and my mother is being controlling

You can say something along the lines of “I really appreciate your help mom, but I got this. Thank you” 😊

Thank you sometimes I don't know how to tell her I'm supposed to learn as I go

I agree with Tierra’s comment. I would also say “this is my first time but I know I’m designed for this. Would you mind letting me figure it out on my own and ask you for help when I’m unsure?” That’s a good intro comment. If she persist after that then I would set a little bit of a harder boundary. She obviously raised a great daughter so ask her for the opportunity to show her what you learned from her great mothering skills.

I had my first baby in April too and I literally had to go to counseling with my mom and will start with my sister this week so they respect my boundaries and let me be mom. What I got out of it was to yes I need to use my voice and say when I don’t like this or that instead of resentment that I would hold for them. I need to speak my mind. Guilt and shame feelings for me with thinking I’ll hurt their feelings is only from the enemy and not from God. Sorry long answer but I have soooooo been through this!!!