I'd like to know too. Is it even possible to leave Merredin and go look for him before the election? I dont want to move the main quest forward if it screws me out of completing my side quests.

I'll never understand why so many CRPGs insist on structuring their quests in a way to screw players out of content if they don't go to ridiculous lengths to avoid progress. lol

Find the ripper is available the whole game, don't worry about that part. You can find them by following the quest for it. I stumbled upon it after you're given free reign in chapter 2 to explore the world map.

(Spoiler)
The location for the Ripper is exactly North West of Merredin at a place called Korrelocking.