Dependent with 1099-NEC filing first

My high schooler son got a 1099-NEC.  I understand from reading here that he needs to file his own tax return, while I can still claim him as a dependent. He just needs to mention that he can be claimed as dependent on someone else's return.

 

He is ready to file, however, I am not.  I am still waiting on some forms and have just filed an extension.  Can he file his return while I file later, or do we have to file my son's extension as well and file together?