I expect that someone high up at Tesla is keeping an eye on the expiration/introduction of subsidies in all major countries so deliveries can be timed to markets that maximize Tesla's global benefit from subsidies.
Since the German 4 k€ BEV subsidy expires with 2019H1 and since during those six months it exceeds the US federal tax credit, I would expect Tesla to start inviting German reservations holders to configure during Q4 so German deliveries can start early next year and keep up with German demand until 19H1 finishes.
All German reservation holders are waiting for the Model 3 to appear on the BAFA list of eligible BEVs here:
BAFA - Elektromobilität
- since that will be a sure sign that German deliveries are imminent.
Btw, hilarity will ensue once deliveries in Germany commence, with the media developing instant schizophrenia:
Das Model 3 ist fantastisch! Aber es ist nicht deutsch!...