Well, lets put it this way, when I get there about 3 hours before game time there is usually already a short line started. And that's for day games. I'd suggest at least an hour and a half-two hours. But that's just a complete guess, really. So in other words - your tentative plan sounds great, you're pretty much assured a front row seat. Nah, night games are not that bad for the bleachers. Everyone is coming from work and doesn't get to the park before 6-6:30. I usually show up an hour before the game and get close seats. As long as your not in a large group you should be fine showing up an hour before. If you get in line at 4, you'll probably get the same seats as you would if you got in there at 5:30-6:00