I don't know if there is superstition in such things, but the thirteenth station will be the transom ... which is shown as station 0 (ZERO). I only add time to get this station in place today, but I'm hoping for a full day tomorrow.
I've had the quote back from Robbins Timber in Bristol, for most of the timber needed for the build, and it total's out at £2696 (US$ 4105). I'll check it out tonight and order tomorrow. They say the lead time is 10 working days, so expect it the first week in December: I always add a few days.