Nah that's stupid. It might delay your trial but do you really think they would just say "oh ok we won't bother"? Of course not - they'd just go ahead with the least biased jury they could find.
It may take a very long time to find an impartial jury if the Trump impeachment goes to trial.
Impeachments are tried by the Senate. We know where to find them, whether they're impartial or not.
You mean, if criminal charges against Trump go to trial, which is far less likely than impeachment (which is tried by the Senate and has no requirement for impartiality) going to trial.