H4 to Student Visa with AOS pending

Hi

My son in h4 and our priority date is oct 2014 EB3. We have filed for AOS and AP and EAD for all 3 of us (me, my wife and and my son)
Question: If none of us use i-485 EAD, will my son be eligible for h4 ->student visa transfer if our priority date is not current by Sept 2025 (he will turn 21 Year) or can we lock his age based on filling date.

You cannot lock the child’s age based on filing action chart.

Your son should be able to file F1 visa.