I am not the one who has them in the PM. In fact, would say they are more likely to be earlier in the day.
And in more thinking about it, should also have mentioned that they often if not usually are associated with subsequent lower GI activity, either solid or air.
FYI, i take Creon and have almost since the beginning when we found that my enzyme production was less than 10% of normal.
And chemo worked well for me pre and post surgery.

The best on your coming Whipple. Sorry to hear about your dad. I think his experience was more the norm than ours.