Hm... take it back to the dealer ?? It's way too soon for you to be experiencing issues with trans/engine but it is new so it's expected to have some bugs. The worst thing for you to do would be trying to remedy it yourself. You have warranty, utilize it my friend !
Maybe that has something to do with the transmission mount? Just a wild guess but not completely out of the norm for an issue like this. Still, like mentioned above have it checked out at a dealer, after all you have a new vehicle with years of warranty and coverage for things like this.
I am quite surprised the delaer spoke about the Ackerman effect which is in relation ship with the steering wheel and correct issue whne turning.
So I did not get your issue, what you mean saying "when setting off in first gear "
In any case go back to te dealer and use the warranty for sure! and maybe ask the dealer try to test another car to try if you can have some symptom on other car..
Do you have the PDK or Manual? Does it do it in both normal and sport mode? My 718S, with PDK, has no problem driving off, just when slowing down, there is a shudder and an accompanying metallic gear sound, when it shifts from 2nd to 1st. Dealer still trying to find the cause.