After you file

The IRS will continue to process stimulus payments until February 5.  So continue to check the Get My Payment website.  

Since you already filed your taxes, you will have to wait until the IRS processes your return and then file an amendment to claim your stimulus payment.  

File the amendment after your original return is finished and you get any refund due to you.

Here is what to do on the amendment:

At the top of your tax return select Federal Review

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That will take you to this screen where it asks if you have already received your stimulus payments.  If you received the first or second payment already, then select Yes and fill in the information.  If you did not receive any payment select No.  If you received the first payment only, fill in that amount and put zero (0) for the second payment.

When the screen is correct, you refund will be adjusted for the amount of stimulus payment that will be added to your 2020 refund.

Then refile with the stimulus payment due as your refund.