Agreed.
It will be their best, if not only chance to knock him out any R primaries.
They are generating witnesses and evidence as we speak and will drag it out to the general election if necessary. Pelosi knows full well it is a matter of timing and doesn't plan to begin too soon.
The timing she's looking for is the time that she has the 218 votes on the House floor needed to impeach the President. Presently she has at most 40, no more. If she had 218, the vote would have happened already. If Nadler's committee were to vote out Articles of Impeachment and she didn't hold a floor vote on them due to lack of yes votes, she would loose her Speakership. If she did hold a vote she would loose so embarrassingly she would loose her Speakership when the Dems loose the House in 2020. There will be no impeachment of President Donald J. Trump.