Harry – I’ve played in the March Championship, the Fall Classic and the WA the past two years and *so far* the WA is the only tourney of those 3 that has used a handicap from the previous year’s tourney. Otherwise they appear to use the same criteria, which is the lowest index revision in the last 12 months, or your current index. The index you submit is also subject to reductions for the usual reasons, such as a lack of tourney scores, etc.
To sum, unless they change handicap criteria this year your WA handicap will be irrelevant. As for the last revision date, just guessing but it will probably be 2/15 given the tourney start date.