No, you don’t. For what you are up to, the grace period is not applicable, just forget about it.
Given Steinberg doesn’t change their policy, at the time you activate your update license, you will get the latest released version of Cubase. If you simply wait and activate your update license - bought at current sale - when Cubase 14 is already released, you will get Cubase 14. Independently of any grace period conditions. Of course, you can’t have 10.5, or any other update, until then… That is the drawback.
The grace period is there for other reasons: In my understanding, it is there for people that have bought and activated an older Cubase version some few weeks before a new Cubase version is released. Sort of protection against »WTF!!1! They release a new version and I just activated the older version yesterday!« This is not the case for you. if I got you right, you did not activate your update license yet.