I paid tax online on 6th January, and then visited civic center on 6th February, just because everyone was saying that they were asking to visit after 15 days.
I was right to visit after 30 days, as they were saying that it takes 30 days approximately. On that day they had plates for people that deposited chalan till 10th January.
You need following:
- Printed copy of your challan (Write your mobile number on challan)
- Copy of CNIC(attached with the challan)
- Old number plates
- Car's file
You have to visit 2nd floor of the civic center, the room that issues number plates is the first room on the left. You give your challan and the number plates and then wait about 30 minutes and then they will call your name, go there and handover your file, they will put stamps on the file, that the older plates were handed over and the new ones were issued (You wait a few minutes more because it takes about 10 minutes)
They hand over your file and new number plates.
Just some minor nitpick, I didn't bring any tool to take out number plates, so I hired a guy that was sitting with number plates on the road side just outside the civic center, he took out 4 bolts and handed me number plates. I visited him again after I received my number plates, he made holes in them and put them on my car, this is the only non time consuming part of the whole process as they are professionals. They took 400 for taking out and putting on the number plates.
I hope that it helps someone, as this thread needs this information.
I am adding about the rush situation: There were maybe like, 15 people in the line. I went there at about 10 in the morning. Even when I was leaving the line had similar amount of people
One more thing 
they did not send me any SMS.
