Its really quite simple. DXB has two peak arrival times: the first between 5:00 am and 7:00 am, the other between 9:30 pm and 1:00 am, local times. If you are scheduled to arrive around those times, carry extra fuel, because you will hold or at east spend a few extra minutes on vectors. Your managers should be forgiving; these hours are known to them, after all, they do the scheduling...
Outside of those times, minimal delays could be caused by single runway ops or a runway change due to winds. Hope this helps.