Yeah, the best time to invade is never. China doesn't want war with Taiwan, and has no real reason for one either. While I've seen a lot of Western thinkers talk about the unfinished civil war, I don't think it holds much water any more. The Communists have won, and have done so very decisively; it's just a matter of picking up the pieces. The main reason remaining for the push for reunification is that Taiwan is the last piece of of the repudiation of the Century of Humiliation. This is literally the main reason for the PRC's existence and so it's an absolute core interest.
But because of what it represents politically (and perhaps spiritually), the value of a peaceful reunification is vastly higher than a military one. And this is before we even consider that an invasion carries a lot of risk, and has very serious economic and political consequences. What all this adds up to is that, as long as there's even a chance of a political solution, China has no reason to resort to a military one. This is especially true as China's position only gets more advantageous year by year.
There are two main reasons for Taiwanese opposition: economic and political. A lot of Taiwanese still believe that China is a poor and technologically backward country that is still under highly oppressive government control. The Pan-Green media loves to play up these messages, and the kinds of things they say can be hilarious. But because it's not based on reality, it's impossible to keep up the charade forever. Sure, the Taiwanese attitude towards reunification isn't going to shift overnight, but China is nothing if not patient, and it's almost certain to happen eventually.