2019 amended return not yet processed - Wait or file 2020 return?

My son filed an amended paper return for 2019.  The status on the IRS 'Where's my amended return' site says - "Your amended return was received on April 28, 2020. However, it has not been processed."  Should he go ahead and file his 2020 return OR wait for the 2019 amended return to be processed?  Any advice appreciated.

Thanks!