This is really, really autistic of me and so I apologize in advance but...
Kamma (or Karma) is the ACTION
Vipaka is the RESULT.
Therefore, you DO good or bad Kamma and then you may get good or bad Vipaka as a result.
Therefore, if someone says 'Can't wait for kamma to catch up with him/her'', they should be saying Vipaka.
Sorry, that's the end of my 'being autistic is hard' Ted Talk!
😂