Schedule C should be 1065 in 2020, Amendment Required for 2020? Can I file 2021 first?

Wife and I own a multimember LLC along with W2 earnings and file a joint return.  For the 2020 return I see I should have filed a 1065 return but instead I filed a Schedule C.  Since it all flows to the 1040 I don't think there is a tax difference.  Do I need to Amend the 2020 return?  If so, can I go ahead and file the 2021 return first (with a 1065 return)?

 

Thanks

Ron