A humble opinion worth a nickel and a cup of coffee (or whatever a cup of coffee costs now since I don't drink coffee).
Those who review ARCs should put their reviews on their blogs close to the time of the book's publication.
I do more than half of my reading on electronic readers. If I read a review of a book that sounds interesting, I immediately go to B&N and order a sample of the book. I have a stack of books on my shelves to read, but many of my TBR books are samples on the Nook or iPad.
If the review appears too far in advance, there is no sample available, and that book falls into a black hole for me. I keep a list on a Sticky Note on my computer, but a lot of times I don't pay much attention to that note.
I prefer reviews of books for which I can order samples immediately. Sometimes this applies especially because some of the best books I read are not huge best sellers. I might only run across one review of the book in the blogs I read. So I like reviews close to the time of publication.
As I said, this is just one person's opinion.