Twister-
There are probably many of us in the same situation. I had less than 100 at interview due to staff job my last year prior to retirement. After 6 months so far in the pool (and two months to go most likely) I have essentially no flying in the last 12 months. Everything I've heard is that once you have the CJO you are good -- if someone has a different experience, I'm sure they'll let the forum know!
Also, for the Yellow Fever immunization -- it is good for only 10 years and not all Immunization clinics carry it. Once you find a clinic that carries it you can ask the tech at the clinic to transcribe your military shot record onto the yellow international form -- they seem to know what to do and they have the blank forms.
-JD