Sorry, i didnt mean to dash all your hopes, I just want you to make a totally informed choice about getting those fish. I dont see why you cant try it at a later date, just get your 220 up and running and look at what you have in the FOWLR.
Having an established reef will help, a mature reef will be more stable and if you cant get them to eat right away, there will be some natural foods in there for them to eat. Also having a few other small fish in there will give them some other targets of attention instead of going after each other all the time.
I also ask you to look at what you have in the FOWLR, if things go bad and one fish ends up in there, they arent going to respond well to another bossy fish like trigger or angel (which most people have in large FOWLR tanks) or even another bossy tank like a kole tang.
Also what sort of delicate fish have you successfully kept? This isnt totally necessary, just something to think about.
Sorry to come off as such a pain, but it really bothers me when people just casually toss around these fish. If you are going to undertake buying a fish that has a high risk of the fish dying, I want to see that people have taken the best possible precautions to prevent that. You have clearly done your research, which is good, but I want to make sure you have thought about your own situation and chance of success in your OWN tank.