Reality
Make your own luck.
Rushing to impeachment without all evidence and criminality in hand is giving Trump an easy exoneration campaign re-election slogan while making Democrats look dumb in the process. Trump actually wants Pelosi to impeach him. Don't play into the devil's hand.
This argument fails because it assumes that republicans will play ball somehow. There is no circumstance in which "all evidence and criminality" will be on hand. The only concern I'd have with impeachment would be if it precludes Trump from prosecution after he leaves office. That option needs to stay on the table regardless.
You're also failing to realize that Democrats are going to look really, really dumb to their own constituents if they decide to sit on their hands after 2 years of saying collusion / obstruction and getting a referral from the special counsel. Moderates will also think they look fukking ridiculous.
Your endgame hinges solely on winning an election and that's proven to be a terrible strategy.