Good idea, MDF is wicked stuff to route,from the standpoint of the fine dust. Make sure you have good dust collection and a good mask.
You might consider cutting out the hole smaller than the finished opening, then cleaning up the saw cut with a router and straight bit, and template. Then turn over the door and use a rabet bit to rabet a shoulder for the glass to set, and for wood stops to hold the glass in place.
Another way would be to rabet from the front and install a decorative molding stop on the front side.
Welcome to the forum you will like it here, I am sure you will get many different ideas from the members.
Herb
You might consider cutting out the hole smaller than the finished opening, then cleaning up the saw cut with a router and straight bit, and template. Then turn over the door and use a rabet bit to rabet a shoulder for the glass to set, and for wood stops to hold the glass in place.
Another way would be to rabet from the front and install a decorative molding stop on the front side.
Welcome to the forum you will like it here, I am sure you will get many different ideas from the members.
Herb