The key thing I learned from keeping Discus is they do best in groups of 5 or more. It seems that there's often a runt, and the rest always stay strong & healthy. So the goal is to keep your eye on the runt and make sure he's keeping up, and not getting to weak & sad looking.
Everyone says don't get juvies, but I'd rather get a nice group of 2.5" siblings an watch them grow. If you begin with a largish group you can remove a bully and/or a really weak runt and still have a nice size healthy group.