On the IRS website it said I would have to file for my 2nd stimulus check with my 2020 return which I did then today I received the stimulus check what do I do now?

[DMarkM1]

You will need to wait for your return to be processed.  Should your return be rejected for some reason, it will be sent back to you and you can make all corrections and updates at that time.  The IRS will not start processing returns until 12 Feb.  Here is the announcement.  

The IRS may catch the error and correct it or send you further instructions, if necessary.  This situation will be a common occurrence given the timing of these events.