First of all, they started an impeachment inquiry, in which they investigate the situation and obtain the documents. But in this case, the president provided them with a partial document that was fairly damning anyway. More to come. About the timing, the Democratic leadership were fully prepared to not impeach and remove this president by an election by the people (really the electoral college) but were forced to move for impeachment because it is there sworn duty to defend this county from all enemies, foreign and domestic. It amazes me how Trumpsters, in both this scandal and the election meddling scandal, criticize government officials for doing their jobs.