I live in a city called Lahore and I was able to find a job in another city called Mianwali (430 Kms away). After moving there, I visit my family weekly or fortnightly (12 ~ 13 days). Should I make Qasr when I pray in Mianwali?
Moreover, It is worth mentioning that I have a house, car, and a servant in Mianwali.
You first have to define what your base location is. Is it Lahore or is it Mianwali? In other words, if someone was to ask you, where do you live, what would your answer be?
Based on the information you've given us, I would say you live in Mianwali and visit Lahore every week or fortnight. That is because you have a house in Mianwali, you work there and you seem to be there on a long term basis since you have a car and a servant as well. In that case, you should pray your salah in full when in Mianwali and shorten it when you visit Lahore.
The scholars have differences of opinion as to (1) what distance constitutes a journey and (2) for how long can a person perform qasar. Regarding the first point, in your case 430km will be considered sufficient distance by all scholars to pray qasar but regarding the second point, there's 3 opinions: according to the Shafi'i and Maliki schools, if a person stays in a place for 3 or less days, he can shorten his salah. According to the Hanbali madhhab, if he stays in a place for 4 or less days, he can shorten his salah and according to the Hanafi madhhab, if a person stay in a place for 15 or less days, he can shorten his salah (source)
This may also help you.
It is kind of unclear to me where you live. I'm guessing you live in Lahore and visit Mianwall for 12-13 days each time?
If so, the rule about praying qasr is when you are traveling for a maximum of 17 days:
It was reported from Asim, from Ikrimah, from Ibn Abbas (RA) that Messenger of Allah (PBUH) stayed 17 days in Makkah & he shortened prayers. Ibn Abbas (RA) said: So whoever stays 17 days should shorten, & whoever stays longer should pray the complete prayer.
Also, it is important to distinguish when one is "technically" on a journey. Wherever you live, or wherever one lives, once they leave their place of residency, they are technically on a journey. It is well established by ahadith that the journey starts when a person starts from his / her place. And the journey ends only when he / she reaches back his / her place. So, if any of us undertake a journey, where Salat Al-Qasr is permissible, it is applicable right from the moment we leave our homes, and we can pray shortened prayers till we reach our home back (source).
So what is the distance where something becomes a journey? Some say 80 km away from your home (source).
Please note however, that some scholars vary of the number of days in which one can pray qasr. I personally have seem some say from as less as four days ("If you are going to stay more than four days you should offer your prayers in full" - source).
What is your permanent residence? Lahore or Mianwali?
If your intention is to keep Lahore as your permanent residence (that means your family lives there), then you can offer Qasr in Mianwali.
When you go to Mianwali with the intention to stay more than 15 days, then you should offer complete prayers.
If your are planning to move to Mianwali for the job (it does not matter how long you stay at that job and hence in Mianwali), then you should offer complete prayers in Mianwali.
Insha-Allah I will find some references too.
