I usually update my Nikon a couple weeks after the release of the update. The wait is to see if there are any major problems with the new release. Although I do have backup copies of the install software for a couple of generations.
The updates include fixes and the code to process NEF, NRW, or new RAW format for the newer Nikon cameras. They some times also add a major new feature.
I would also check for new firmware updates for your cameras.