Filing a new H4 EAD with 6 months pending on H4 Visa

My H4 and Spouse’s H1B will expire on July 15, 2021.
I am eligible to file H4 EAD as of Dec 1, 2020.

My spouse’s employer may file H1B extension and my H4 extension around Mid Feb 2021.
Should I apply H4 EAD application now or wait for extension to be approved by March 2021?

You will need H1B extension receipt number to file H4 EAD. So, you need to wait.