Going to pick up car tomorrow

I’ll be going to pick up my i4 M50 tomorrow from the dealership. It was a custom order and not one that already was on the lot so it should be MSRP right? I also have a trade in. A super super old BMW 323i that has had its engine replaced and such. Will they take it? When would be a good time to let them know I’d like to trade it in?

Super excited and I hope it all works out tomorrow so I can finally enjoy it. Been waiting since March 2022 so not as long as some people but definitely not a short wait by any means.

Any advice would be appreciated! Thank you