First of all congratulations, Allah naseeb kare.
Verify the Auction sheet to ensure the odometer reading. Change it's Engine oil (5w30 is recommended oil for Vitz) immediately with change of air & oil filter. Change it's brake oil to be on safe side. If odo meter reading is verified then change CVT oil on 40000 km mark, if not verified then changed its CVT oil with Toyota CVT TC oil. ( The oil shop owners will tell to top up the current oil which might seem cheap but will be harmful for your car.) Get it changed from Toyota. Get it brake pads checked, if necessary replace them. Do not spray any oil under the car body when going for service of car. Get it hooked with OBD 2 scanner to see if there is any fault (If you are in Lahore, I can do that for you free as I have my own scanner). Do not let desi electricians to cut open the wires they ultimately ruin your car.
Enjoy the ride 