i have an oscar with a few fish, pleco, 2 convicts, and to blood parrots, enough space and enough filtration and hes now 9" and doesnt bother anyone, but theres no telling now when he'll turn... its now about when they grow up, but about when they turn sexual maturity! once that happends, you'll know... i havent been there yet but i am prepared to move a bunch of fish when it does happen! just keep in mind like others have said... you're fine now but you HAVE to be PREPARED to MOVE these things later or even split them or sell them or sell one... 2 oscars is a lot and u must have the space...
my thoughts is since you have 2, that may cut ur time in half with the decision time!!! BE PREPARED!
also having 2 is real risky in the future, cause you cant tell the sex... so even though they get along their whole adolescence, once they reach sexual maturity, they'll realize who they are and fight till the death... and even if they are different sex, still be prepared!!! i have no experience with this but HUKIT does... WHERE IS HUKIT (everyone is asking) but i know hes had it happen just this passed summer... had a breeding pair i believe and woke up and one wasnt with him anymore...
all in all guy, BE READY! haha its an ominous situation you're taking on! good luck!