After you file

@xmasbaby0 

 

IRS says:

"if the IRS has not processed your 2020 tax return as of the payment determination date for a monthly advance Child Tax Credit payment, we will determine the amount of that advance Child Tax Credit payment based on information shown on your 2019 tax return."

 

If your dependent list is the same or non-empty for 2019 there should not be any delay.