The impeachment proceedings are nothing more than an attempt to get Trump out of the White House through non-democratic and unconstitutional means.
Impeachment is for CRIMES committed by a president, not as a substitute for a legitimate election.
There's a reason there have only been 2 other presidents impeached in the history of our nation -- 3 if you count the inevitable impeachment of Nixon which never had the chance before he resigned.
The reason is because Presidents are elected by the people. Removing a president goes against the results of that election. The deeds have to be so over-the-top illegal that they undermine our trust in the president and his ability to execute the responsibilities of his office.
EVEN IF it was proven Trump was targeting Biden via Ukraine to eliminate him as a 2020 opponent, does that even have a criminal statute associated with it? The closest Schiff can come is "abuse of power," but since the money to Ukraine was not withheld contingent on some investigation being announced, I see no relationship between the two.
This all goes back to 2016. Ever wonder why Joe was so reluctant to announce he was running? I wonder if the fact Trump was not being impeached over Russia-gate 1.0 changed his mind? If Trump gets to the bottom of the 2016 election interference, I have to wonder, since most of the interference seemed to originate in Ukraine, how many of Biden's fingerprints would he find? Becoming a candidate was a good way to cast aspersions on any criminal allegations from the Trump administration.
As for timing, all this is happening AFTER the Mueller Report. Until then, Trump had his hands tied as to any Ukraine or other 2016 election related investigating. He had to wait for Mueller to finish and get out of the way, or be accused of obstructing.
Everyone likes to argue each of Trump's decisions in a vacuum. In reality, these actions are all part of a much bigger picture -- one which the artists are frightened Trump will piece together and use to send many of them to prison.