I had a question similar to this yesterday as DW and I are going to make the plunge with OL.
It is a question that was not dealt with on their FAQ's, so thought I would throw it out here to clarify if anyone else has the same dilema.
We usually did the first 2 weeks in Dec, but last year was ALL of Dec leaving Jan 1.

This year it will be Dec 8-27

cool1: again).
So I was wondering, if we sent the locker back on the 27th, that would be our Anniversary date, but what if next year we went home on the 28th, or later (Jan 1st, say).
That would put us into our next Ann'y year, no problem, but then the next year we went home on the 23rd, would that be considered twice in one year.

Please note, for this scenario, I am not taking into acoount the 2 free visits for 3 years, I am looking 3 years into the future after that is over, and only one free visit per year.
Phoned John at OL (super nice!) to ask, and he confirmed that your Ann'y date is the first time you send your OL
back, but your subsequent "visit" dates are based on
delivery of your OL to the resorts, not the pick-up date.
That's what was confusing me.
So all is cool, consider us another OL client.