I completed a full review of my mental calendar from 17 December 2011 in December, taking a month and reviewing the images pinned to each day as memory tags for subsequent years. This brought me up to date.
There were blanks, some of which I was able to complete as subsequent years or months triggered associations. The earliest years were the easiest to complete as I have reviewed them so many times already.
January has just finished and I completed as far as the end of October. Accordingly, I've started February by running through November, December and January tags. I have 12 x 9 years = 108 months to cover, so need to cover about 4 months per day.
I will keep to the three-month window. It will have advantages as I was finding when I picked up on each month that I might have to scan the preceding month to orientate myself.
I changed the review of the past 12 months in January to make it more manageable. I had been reviewing two days per week for the whole year. Moving this window on a day at a time, so there would be overlap. To save time, I did 6 months at a time, dispensing with the overlap. So one day, Monday and Tuesday for January to June, the next Tuesday and Wednesday for July to December, then Wednesday and Thursday for January to June, etc. This half the time.
Again, it is the more recent days that are harder to track down, but I now keep a diary and note the memory tags at the top of the page, so can flip through that to remind myself. This is a practice I'm following only for the last month or so of images, as after that they are generally entrenched enough. It's a crutch, but now necessary and does not negate from the benefits I gain from the mental reviews of every day of the past 9 years.