When I ordered my car (not through MB) in Dec 2020 I gave the salesman an absolute date that I needed it by, February at the latest.
I really wanted something pre-built to remove any risk of delay but they couldn’t find one in stock in the spec that I required.
Needless to say it didn’t arrive in time and they just kept fobbing me off until it did. Everyone’s experience will be different, and I’m well aware that chip shortages and factory closures aren’t their fault, but I could have made alternative arrangements if they’d just been open about it. Moral of the story is to hope that it’ll arrive by your desired date, but definitely have a back up plan in case it doesn’t!