hai dude!
Its not strictly required that you be there before 3 hours. Its just to make sure you won't miss your flight. Matter of fact, it takes long time for checking bag, and all for international flight then domestic......and other thing is if the airport is not busy it won't take long time. Once one of my fren missed the flight.......so we had to pay some $250 extra to re-schedule the next flight. and one more thing they wont' let you check in if you are at least one hour early. So, at least 2 hrs is needed......but its not you h ave to.........ok dude....just don't miss the flight..............
good luck!