Retired ARNG here. To be safe, continue going to drills until retirement orders are in hand.

I submitted my retirement request upon receipt of my 20-year letter. The date on the request was 7 Sep 01. I'm certain the date of the request was the reason I was allowed to retire. The 20-year letter actually arrived shortly before my 20-years-of-service date.

I attended four more paid drills before the orders were cut. There was one year where I had service in the ANG, USAFRes unassigned officer pool and the ARNG. It took several attempts to get all the points combined to get a good year out of it. Since you said you were prior service Navy, you might have a similar situation. I hope you don't.