First up, what would you guys go for if you had the money, etc. XR6T Sprint or XR8 Sprint? I've been hopping for the last couple of years that you'd be able to get the "G6ET Sprint", I would have seriously considered swapping over to one...
When I got my G6ET brand new it didn't get delivered straight away as I wanted the Cream interior and black exterior and the cream leather was only done to-order. The dealer I went through pre-purchased four G6ET "to-order" each year to cater for customers like me. If no one came along, they just specced it with one of the popular colours and no extras. It meant I ordered in I think early April but the car didn't start its journey on the Production Line until 29 May from memory with delivery on 29 June.
Had I wanted to change colour, interior, spare wheel, etc. I was told I could do any of that up until whatever the date was for the Friday before 29 May (it was 4-5 days).
It's a pretty safe guess that's what will happen here, particularly for large dealers. They will have reserved a number of slots on the Production Run (say 41, 87, 126, 175, etc) and they will be able to change any details for the car (colour, interior, factory extras) up to a certain date. The early ones are likely to already be in production in popular colours so if you want one in an odd colour or with extras you'll probably have to wait a few months.