So I've been on terminal retirement leave for 4 months and it's almost over. (Army 20 years)

My CAC expires on the same day I retire, when do I go to get a new ID card? Like do I have to wait till I'm officially out and go through the PITA of getting on post with an expired ID, or is it one of those like a week beforehand areas? One of those random things they don't cover in clearing or any briefings that I now have no idea about.

The nearest base is about 2 hours away so I don't wanna have to drive more than once to get an ID card.