Do you receive a 12 month extension for Non-O student and guardian visas on the same day of application?

There is no Non-O student visa 🙁 so I am guessing you mean a Non ED visa/extension

Unfortunately I've seen immigration offices do it BOTH ways, where the child getting the ED extension and the parent getting the guardian extension get under consideration stamps and then go back to the office 30 days later to get the year extensions inked in

AND

I've seen them issue both yearly extensions on the same day without an under consideration stamp.

So I think you're going to have to slog on out to your immigration office and find out what procedure they follow for ED and guardian extensions.

The good news is if they accept your documentation, take your 1900baht for the extensions you'll get them, as I have never seen an ED extension or guardian extension rejected after the under consideration period runs down.

If they're going to reject your application they'll do it right when you apply not wait a month to do it