Okay, I dug out our City Pass booklet. We booked our vacation through the
Disneyland website, including the SoCal City Pass. (The DL part anyway.)
We wanted to do San Diego first, though, so we also booked a hotel room in SD for the days prior to going to DL (used expedia for that part.)
Our trip (including SD and DL was October 14 - 21st, 2006. When we had the City Pass mailed to us, I noticed that the start date stamped on the booklet stated "
Valid for 14 days beginning Oct 19, 2006" (This was to be our first day in DL.) I panicked. We had reservations already in SD and I wanted to be sure that we would be able to go to Sea World and the Zoo prior to the 19th, so I called. The woman I talked to told me not to worry, that I would be able to use the City Pass before we went to DL, as long as we used the passes within the time requirement (earlier I thought 7 days, but on the booklet it says 14 days.)
So, long story short - we used our City Passes to go to the Zoo on the 17th and Sea World on the 18th, then began our DL stay on the 19th. To be honest, neither the zoo nor sea world even looked at the date stamped on the cover of the booklet.
Hope this helps. Have fun!