Well if you plan to give the players an extra day you could exchange the 6 fatigue for a severe hangover (add 2 misfortune to every action for the morning?). As for the cult track filling up, look at what the players have actually found out and maybe you can do a light behind the scenes reset. Give the players an extra day to sort things out and discover the rest of the mystery.
Perhaps the Schlaff was administered a day early by an overzealous member of the cultists and now the cultists are nervously planning to poison everyone for a second time. That will give these people something to do while the players look for the dwarf.
Are the beastmen behind the abduction? Maybe the have stolen a (freshly imagined) all important ritual dagger from the cult, or one of the books the cultist need to finish their ritual. That would slow them down, maybe one or two will travel with the players.
Or, if it is a fight you like, perhaps the cultist take over the house as the players rescue the dwarf. Reclaiming a hunting lodge, saving what remains of the real inhabitants and fighting a daemon after taking on a forrest full of beastmen to save a wounded dwarf. Well it sounds heroic…
Always remember that as a GM you know much more then your players ever will, which gives you a chance to improvise and change to fit the actions of the group. In the end the scenario's that turn your hair grey because they went off the rails in the first minute are the ones most fondly remembered by everyone.