Totally okay to do that, in fact the offices are telling people TO get the covid extension to give time for getting documents or seasoning the funds etc.
As
@El***
said it is up to the immigration office, as a rule you can apply when you have 30 days or less left on your current stamp.
So you're fine to go apply now if your funds are seasoned and you have the documents.
Remember when you apply you'll turn in your paperwork, pay the 1900baht, get a 30 day under consideration stamp & during that time the immigration office might or might not send someone to your house for the in home visit. Then you go back on the date that under consideration stamp runs out and they ink in the rest of the 11 month extension (the 30 day under consideration stamp is the first month of your new year extension)