I was actually very lucky with my car. I went for a test drive in an S5 on the 17th May and expressed an interest in ordering one. I went along with the spec I wanted and got a final price etc and was just going to think about it. So then a couple days later I got a call from the dealer saying he found the exact same spec car I wanted (brand new, unregistered) up north somewhere in a showroom, sweet! So I put a holding deposit on it and it was delivered on the 29th May and I picked it up on the 31st.
So from putting the deposit down and picking it up, I didn't even have to wait two weeks, so I considered myself pretty lucky
I was told originally that it would've been around 12 weeks to order/build/deliver.