How can I schedule a visit to the Ming Tombs, not having time enough to see everything?

Well, in general, the suggested sightseeing time is 2.5 to 3 hours.
If you still don't have enough time, it's advised to tour around Dingling Tomb first. This scenic spot is the must see in this area. It covers an area of 44 acres. In there, you can also see many rare and exquisite exhibitions.
On the way there, also have a stay in the Sacred Way, which is famous for stone statues.
Have fun!