I've been getting them as soon as they come out and photograph them as soon as I get them. So according to my pictures this is when they arrived...
Cocobolo - February 5, 2005
Black Micarta - April 14, 2005
Evrina - July 28, 2005
Tiger Coral - October 31, 2005
Apple Coral - March 26, 2006 (for some reason, the Collector's Club numbered ones, like mine, were about a month or more behind the rest)
Gold Lip Pearl - July 26, 2006 (these kind of trickled out, and mine was quite late, a few were released in late May/ early June)
That should give you an accurate picture of the sequence, and a pretty fair idea of release dates
Next one due out, and from what I understand the last one scheduled for 2006 release, is the Turquoise. No word on what comes after that.