Looking forward to running this adventure path, my players are really into the horror theme and I'm hoping to do it justice.
I had a few questions about the first adventure.
Firstly, whats to stop the players from charging off to Harrowstone as soon as the funeral and the reading of the will are concluded? Should I try to discourage this? I'm a bit concerned they'll try to tackle the whole dungeon at once and (being level one) will probably get slaughtered trying to do so.
Second, one of my PCs wants to play the son of Petro Lorrimor. I'm uncertain if this would cause issues later on in the adventure path. On the other hand though, it might serve as a good motivation to really be interested in solving the professor's murder and being involved in taking care of his affairs.
Nothing will stop the players from charging at Harrowstone except for your own pacing and how fast you give out information. That said, there's plenty to keep your PCs occupied before you start nudging them towards the prison; consider using the plethora of added material to flush out Ravengro and fix the Trust mechanic.
Having a PC be the son of Petros gives more motivation for discovering the truth of his death. It also could make them a target of the Whispering Way in book 6 if you're going to use the "Kendra is the Vessel" way that most people did. Having the same bloodline means he could be the one to host Tar Baphon, which could create all sorts of RP opportunities.