6-8 Weeks is about right for a car staring production within a few days of placing the order.
Our car is scheduled for assembly on week 9 and delivery on week 12. This is the end of week 4, so you will probably get your Z just before we do.
The models and equipment (standard and optional) illustrated in this post reflect my misunderstanding of vehicles supplied by BMW AG to the German market. In other EU member states, the truthyness of my posts may vary. Please ignore this post. Subject to change.