Community tank for beginners?

Hi, I'm about to start setting up a 65 gallon aquarium, and I'd like to keep discus.

What I wanted to do was start with some hardier fish that would be good in a community aquarium, then once the tank is established, add discus. But I'm not sure if a 65 gallon is big enough for doing that. If I have 5 or 6 discus in the aquarium, is there room for other fish? And if so, how many other fish could be added? Could I have a quartet of corydoras, or is that too much?

Or, am I better off just keeping discus by themselves for my first discus aquarium?