Is it permissible for me to shorten and combine the obligatory prayers before traveling in my country, given the long duration of the journey and the uncertainty of finding places to pray?

It is not permissible for a traveler to shorten (qasr) and combine prayers until they have begun their journey, based on the Almighty's saying: "And when you travel throughout the land, there is no blame upon you for shortening the prayer." Shortening is thus conditioned upon traveling in the land, and the ruling for combining prayers generally follows that for shortening. Therefore, if the time for prayer begins while one is on their journey, it is permissible for them to avail themselves of the concession to shorten the four-rak'ah prayers and combine the two prayers of a time slot (Dhuhr with Asr, or Maghrib with Isha). However, it is not permissible to perform a prayer before its time begins under any circumstances, unless it is the second of two combined prayers, in which case it may be combined with the first as an early combination (jama' taqdim), or the first may be delayed to be combined with the second as a delayed combination (jama' ta'kheer). This is the view of the Shafi'i, Maliki, and Hanbali schools of thought.