In the test report from autoexpress.co.uk there is the first concrete information about CarPlay and Android Auto:
All #1s feature adaptive cruise control, heated seats, a 360-degree camera set-up, LED lights, Apple CarPlay and Android Auto (from October-delivery cars – customers who receive their vehicles in September will be offered this as a free over-the-air update), climate control, all-round parking sensors, a panoramic roof and 19-inch wheels. There’s a three-year, 30,000-mile service pack included, too. Premium models add a Beats stereo, a head-up display, matrix LED headlights and park assist.
Accordingly, vehicles that were delivered between October and September should get the update to CarPlay and Android Auto free of charge.
I'm now strongly assuming that it's October to September, because it's about the British market and because delivery is still to come. I would say that means for us that anyone who gets the car before the end of September gets CarPlay and Android Auto for free. 
