Im fairly new to 121 flying so I would like to hear some opinions on this.

On a layover at a small outstation, you wake up with a head cold or other sickness that you felt would prevent you from completing the rest of the trip. Feeling well enough to fly the one leg back to the main base, would you give crew scheduling a heads up before flying the one leg so they can have enough time to get the rest of the trip covered? Or would you wait until you landed, knowing it would likely cause a delay (or possible cancellation) of the next flights?

Ive heard its ok to call before (and I would like to be helpful when possible), but would this open you up for legal issues as to whether or not you were fit to fly the one leg back to base?