Gee - don't ask me, I don't find out about map updates until I read about it on the Garmin public website (or, sometimes, here). I test the hardware and the software that runs the GPSRs, not the maps.
I wouldn't worry TOO much about missing out on the latest map version, though. A few years ago, when new map versions only came out once every 18 months, it made sense to try and buy at the beginning of a map cycle. In the last few years, the revision cycle has shortened up - if another revision comes out before Christmas, that will be the second revision this year. How much could have changed in the last year, honestly? A few roundabouts, perhaps?
Back when the version numbers were 2, 3, and 4, the cartography was incomplete, and everyone eagerly awaited a new version to see what had been added - often, to see if their own neighborhood had been added. Now, the street level detail coverage is 100% in many countries, and the only holes that remain to be filled are either countries with 'exceptional circumstances' (Ireland), or really remote places that no-one is likely to ever make it to (Northern Norway). The faster the map revision cycle becomes, the less important the revisions will become.
Think of it the way you would think of a paper map. A paper map is generally considered up to date for about 3 years after date of publication. Once it gets past 3 years of age, enough things have probably changed to make it worthwhile to buy a newer, more up to date paper map. Electronic maps are no different. If the current release - what is shipping today - is (for example) one year old, then it has another two years useful life in it. If you think you will keep that same GPSR for longer than two years - then you might want to pay attention to the revision cycle. Even then, though, it could be argued that there's not much point in getting stressed - if you buy today, and a new revision comes out tomorrow (and you can't upgrade free), big deal. Buy an upgrade in 2 years, and you then get 5 years useful life out of the GPSR (the original maps for 2 years, and the upgrade for another three) for the price of one map upgrade. In 5 years, the GPSR - meaning, the hardware - will be close to being an antique anyway.
On the other hand, if you think it is probable that you might get rid of the GPSR before the maps are 3 years old (trade it in, sell it to someone, whatever) - they why worry? You will have fresh (less than 3 years old) maps no matter whether you have the current issue or next spring's issue.
Much ado about nothing, I think, now that the revisions are coming faster and faster. For what it's worth, aviation maps (the paper ones used for visual navigation, not the instrument charts) are updated on average once every
seven years. When was the last time you looked up and saw a lost airplane flying around in circles, trying to read the name of the town off the top of the water tower?
Michael