Actually, my hypothesis is that you'll probably have your best results playing at peak hours. I think this for two reasons. First, I seem to run into the most trolls early mornings on weekends where I very rarely encounter them on weeknights when I play after getting home from work, or later in the day on weekends.
This could just be a statistical anomaly, however, I think this observation may make some sense. What causes a person to troll? I submit that a given person is most likely to troll when they are bored or frustrated. At peak hours, let's say 7:00 pm on Thursday night, you get a bunch of people like me playing. We work (or have school) in the morning, we only have time for a few games, we're not going to waste them on screwing around.
On off peak hours, say 6 or 7 am on a weekend, you might be running into people who have been up gaming all night, have had a string of bad games, or maybe they've been screamed at a bunch, or whatever. Regardless of the reason, to me it makes sense that the odds of running into that frustrated troll who just wants someone else to feel his pain could be higher.