Short Answer: Soon and Often.
Microsoft has done an above average job of publishing the 5 year plan for GP for nearly a decade.
With Major release milestones, they are giving clients ample time to schedule, budget and prepare.
There is a small army of developers working for you, driven by your yearly maintenance. Daily they are striving to improve the product for the better.
Why not take advantage of this effort!!! With any complex program, it is impossible to test for every possible installation configuration and setup.
So, it is impossible for them to 100% guarantee that every release is flawless. However, as identified issues arise there is an intentional effort to resolve in with the intermit patches.
Meaning, that if you are
So, when should you upgrade?
Well, depending on your specific environment, including but not limited to, Hardware, SQL version, Customizations and Integrations,
along with installed
If you are on an old version, GP2013 or lower, most likely you will need to reevaluate both your hardware and SQL instances.
This is a great time to
These older versions are no longer supported and the longer you wait the more difficult upgrading will become.
Upgrade often, every patch, service pack, enhanced released, or major release should be evaluated and especially reviewed for the latest system requirements, paying extra attention to no longer supported software, and systems. If you have ISVs, they usually get an advanced copy of major releases; check with each of them on their respective compatibility release before planning your upgrade.