It' quite straightforward, Ulf.
The next available hull number is reserved after a pre-payment of around 4%, which is almost fully refundable until six months before they start building the boat. Then follow fractional payments, with the last 30% due on delivery.
To be honest, I must somewhat clarify the delivery in april 2012. We could already have the boat around november this year. I certainly don't mind a winter sailing trip, but we prefer not to spend two weeks test-cruising in Brittany and then sail the boat back to Belgium in december. After all, we're cruisers...
Structures is pretty open (in my discussions with them), on finding that slot for the delivery date. On the 10.50, when I last spoke with them, there were a few slots that could have been available before the full 2 1/2 year wait list as some (a few) buyers wouldn't mind postponing delivery due to various reasons. I'm not sure if this is still the case because it's been a few months since I've spoke with them but I would imagine there are slots in well under 2 years.