If your makeup artist does a good job you'll look as fresh. Of course how heavy your outfit is plays a big role in how tired you look by the end of the day. Also during the shoot don't do a lot of unnecessary walking around.
Don't know anything about how Pakistani makeup artists do the makeup. I got mines done by 5:30 due to a photo shoot, my makeup was still fine at 8:30 when the actual event started & was perfectly fine till the Rukhsati at 1:30 am.
As someone mentioned humidity in Karachi. Keep blotting sheets with you if you have oily skin & a lip liner, lipstick & lip gloss. That's all you'll most probably need for touch ups. As Mahi suggested do let your mau know what you plan. Maybe you can ask her for a touch up before the actual event starts.