It depends on the commands, training commands might hold someone longer than operational commands. I say this because of friends on both side, it seems to be the trend it all depends on the manning of the command i.e. if my PRD is OCT 2023 and I got picked for SNA or NFO on the May board the command will hold me as long as possible because there will be a gap in the billet i am filling. I got a friend that found out he picked up SNA in JAN 2021 and he just got his OCS date APR 2022.
I understand they want to hold people as long as possible, but no one is that critical, you never know when a person you see at the end of the day will not make in to work the next day, sometimes it is just out a few days, sometimes you never see them again, the work still needs to get done and a command needs to be trained well enough to adapt. I have seen this happen a few times, I had a CO that let a guy go right away as he didn't want to hold him back from his dream so we dealt with it, I had a CMC who's wife suffered a stroke when I was on "remote" shore duty and I never saw him again but we got by.
Just be careful for the next 9 months!!