Im not so convinced its as clear cut as it used to be
Ye sthey still have targets, but with most cars built to order and that being some months there is no point rocking up two weeks before quarter end and expecting to spec a new car to your spec.
So your going to need to be able to accept one they have, ie a pre pregistered one. Which are normally ones they have put factory orders in against, assuming they will be able to find a customer for and amend the spec of at a later date.
When i was looking 18 months ago I couldn't get an immediately available one as cheap as a new one. Because the ones they already had they were relying on selling to someone who couldn't wait
There is supposed to be a fair stock of German marques currently that have been help up by WLTP. Whether thats true or not who knows but its the rumour I have seen