If you had a baby in 2020, you should have included her as a dependent on your 2020 return that you filed a few months ago. If you didn't, you've got a refund coming, and need to amend. If you already had her on the return, then TurboTax would have calculated what payments you were eligible for, and included them on your return. Review your return to see whether you got the credits. They will be on line 30 of form 1040.
Was your baby listed as a dependent on your 2020 return? Which box is checked? For Child Tax Credit or as Other Dependent? It should be the Child Tax Credit. But either way you should have got the $1,100 (500+600) Stimulus payment for her on line 30 Recovery rebate credit.
Oh, you said when you file 2020? You didn't file it yet? Do you still need to file 2020? A child born (even on Dec 31) is considered to live with you the whole year. So be sure to pick the Whole Year at the top of the drop down box.