A friend in Kyoto has completed the pilgrimage twice in two years (2007-2008). It took him 42-45 days each time.
It's not necessary to complete the entire walk at one go, and most people do not. (There are a lot of "it is not necessary" involved in becoming a Henro). One fashions one's journey according to time, ability, and fortune.
I am going to do walk part of the Shikoku Pilgrimage this February. It will be cold! I am ordering long-underwear online

More here --
Pilgrimage to the 88 Sacred Places of Shikoku
http://www.shikokuhenrotrail.com/shikok ... shima.html" onclick="window.open(this.href);return false;
The Shikoku Pilgrimage Route
http://www.davidmoreton.com/Shikoku-Pil ... -Route.php" onclick="window.open(this.href);return false;