I have to O's that are 5-6 inchs they have been together for little over a month. My questions is if they are two males when will they aggresstion start(not that i want it to)is this something that comes on early or around maturity.They are swimming sleeping and moving gravel together in harmany..

aggression or territorial supremacy starts at 8 to 10 months.
during early period, they do some mild bullying but not hurting
to much. same is true when you have both female, they do not
fight that much. they even laid eggs but no fertilization.

You may never encounter aggression, not all Oscars fight. However, as Paul has said, there is often little bit of banter between them that you don't have to worry about.Oscars can often be very friendly one minute, and then the next minute, chasing each other around the tank and being very aggressive. Many people get worried when they see this happening, you've got to sit back and observe them for awhile. Nine times out of 10 they are friends most of the time and just have a little scrap occasionally which is nothing to worry about