Luke 2:6 So it was, that while they were there, the days were completed for her to be delivered.
God’s timing is far beyond our control or our understanding; whether He wants to use the whole kingdom to make one thing happen or to use one person to change a kingdom, God is in control.
Human’s tend to try and stick to timetables and calendars in order to try and keep things under control; God has time under His control!
We live our finite lives and try to pack in as much as we can into those lives; God controls them.
We may take a long while to plan a surprise for someone, but God can use many centauries because He is in control.