I spent about a year in /r/askcarsales before I made my purchase, I found it kind of informative. Some people here may have a problem with that subreddit, but what everybody there says is pretty consistent. They find it annoying when people try to “pull a fast one”, because they encounter it on a daily basis, it’ll never “trick” them into giving you a lower price.

Realistically they’ll probably ask you if you have a trade in and if you have financing figured out fairly early in the discussion anyway

By all means do that things, I’m not saying not to. But from my understanding I don’t think it’ll benefit you. Somebody may reply and say they’ve had opposite experiences, who knows.