Recently married

I got married last February 2021. I filed for a name change at USCIS (permanent resident) and it’s still on process.

My questions:

1. Do I file my 2021 returns as single?
2. If I can file as married filing separately, do I have to wait for my name to be change with the USCIS and SSA, I understand that there’s a deadline to file the tax returns until April

Thanks!