Is setting the timings of Ihram a prophetic ordain related to those times?

Answer

In the name of Allah, these times are for all of the mankind at all times until the Day of Resurrection. Allah Almighty has said (O people, I am Allah’s Messenger to you all). It is not intended only for the people present in his era and his apparent life, but all human beings - until the Day of Resurrection. His laws including defining the timings are the core of Sharia. Allah is the Guide, and Knowing.