Why didn't God send the Quran from the beginning?

If God is omniscient (knowing the past, present and future) why didn't he reveal the Quran earlier instead of these previous revelations that have become corrupted over time (Torah, Zaboor and Injeel revealed to Moses, David and Jesus respectively)?

Dr.,Zakir,Naik,Bible,Quran,Qur'an,Koran,Islam,Muslim,Christian,Christianity,Religion,