i think you need to focus on other thing than improving your T3 game play.
But if you need advice in order to know how to play the T3 aeon.
- Try to avoid power stall it make the shield of your harbi down, and they are significantly more vulnerable.
- use the range of your T3 unit, try to use them like aurora, when you are against T2, use attack move.
- when you get T3 before your opponent try to abuse that fact, by dropping 1 harbi on the high ground, and to send them in little squad to do some raiding.
- think about some flak in your T3 army so you don't get beaten by air.
- harbi vs percy is a difficult match up. I would advice it only for pros. When you see your opponent reached the T3 phase, you should focus on sniper bot, and some mobile shield to protect them from bomber. And of course use the range of the sniper bot.
- in general when you rush T2/T3 try to avoid the opponent acu, so he don't OC your first powerful unit.
but as i said, there is more to do in general about expending, reclaiming, not suiciding unit (giving reclaim)....
hope it helps