When I browse channels to find something to watch I want to know whether sitting through an ad is worth my time. If you show an ad as soon as I open a channel, I'm leaving, because I don't even know if I care enough to sit through the ad. That's how ads work. They are by definition annoying and an obstacle, so the question is always, is it worth staying. If the channel is worthwhile, I'll sit through the ad. I've left channels innumerable times because an ad comes first and I don't even know if I want to stay, whether there's an ad or not.

Also, too many categories on this feedback site, I don't even know what difference some of these are. I don't work for you, I'm just a casual viewer. I'm sure most of us are, hopefully, because twitch is a last resort of entertainment.