That's an awfully big tank, congrats!
I would strongly advise you to make a list of all the fish you want to eventually have in the tank, before you buy any. Even a responsibly stocked reef tank is putting wild animals in much closer proximity to each other then they naturally would be. That comes with risks of aggression because of their territorial nature.
Luckily fish are pretty stupid. Sometimes you can trick them into sharing space by adding them in the right order. So if you put the shyest fish first, they have a chance to scope out their safe place and they'll be less likely to try to run away (down the overflow, through the screen on top, etc) or be all stressed out and sickly from homelessness. Then you add more aggressive fish, and they take the tank as they find it, they aren't as prone to attack a smaller fish that was there first.
By that logic, if you add your clowns now, they will bully any less aggro fish you add after. There's lots of fish less aggro than clowns, so you'd be narrowing your options a lot.
Another benefit besides territory is diet. Lots of people buy a wrasse early on because they are fairly hardy. While they aren't picky eaters they do gobble up a lot of the wild food that other fish depend on. When those people later decide they want a mandarin, they are out of luck because it can't compete with a wrasse and get enough food.
Lastly, it's just easier. You don't want to be the guy that bought a blue devil damsel in the beginning and then went crazy trying to trap it like wile e coyote after it killed $500 of fish he tried to add after the damsel decided it owned the tank.
If you make a fish list the smarties here will give you great advice on compatibility and stocking order. It'll save a lot of time and headache. You have so many options with such a big tank, you'll be glad you took your time in the beginning
PS welcome to the forum Scott!
