If paper towels are dry the next day then the assembly most likely was properly done and the fork is not leaky.
I find it important to change the oil in such a way that the fork is left overnight before riding.
I remove paper towels before the ride the next day.
Another useful trick is to put a little bit of Slickoleum on the end of the stanchions before sliding lowers on them. This way the lip of dust seal does not roll inwards. Try and see!
Here is the picture:
