Should I Feed Him Now?

I usually feed my ball python on Sunday. I noticed last Sunday he was going to shed soon (blue eyes and very dull) so I didn't feed him.

He shed last night. Should I offer food now or wait until his regular Feeding day on Sunday?

I don't think waiting till Sunday would hurt if you want to keep him on a regular schedule. Without knowing more details it's hard to say. If he is a hatchling I'd feed now. Still your choice. Not going to hurt anything.

I would wait, one skipped meal is nothing if the snake has been eating regularly. If you do decide to feed today, change his feeding day to Wednesdays so he keeps the weekly interval.

Has your snake refused food while in shed before? I always attempt to feed on the scheduled day even if the snake is deep in blue, most of mine will take regardless of if they're in shed or not.

Completely up to you. No harm in waiting, no harm in feeding now.
I personally feed the day after a shed with my BP. He refuses while in shed, so I just feed after he sheds and start a new weekly schedule.