Is it permissible for a traveler working in a non-Muslim country for an unknown duration to shorten and combine prayers, and what is the ruling on delaying the Dhuhr prayer for fifteen minutes after the time for Asr begins?

If a traveler knows that he will stay in a country for four days or more, he is not permitted to avail himself of the travel concessions of shortening and combining prayers immediately upon his arrival. Rather, he must perform the prayers in full at their prescribed times. The rulings of a resident become applicable to him from the moment of his arrival if his need will not be fulfilled except within this period. If shortening prayers is not permissible, then combining prayers is also not permissible unless there is another excuse, such as illness or rain.