I'm working on a campaign where the adventurers start as commoners, who are dropped in a forest full of danger when the carriage they were riding in is ransacked by werewolves. I want the players to start weaker than a first-level character would be, to reflect that fact that they're not really adventurers and haven't learned how to fight. After the first session or two, after a few days or weeks of trying to survive, they can choose a class that reflects the fact that they've gained skill as an adventurer in the forest. First of all, do you think it's a good idea to do something like this, or should I just start my players off at level 1? Secondly, should they start as some generic "commoner" class with no abilities and get to choose a class later, or should they start with their classes but at level 0, with their proficiencies but no class features.
I recently did this and I thought it was great. I think the players liked it at the end, but they were NOT happy about playing as Commoners. Everything was "not fair" (which as the DM seeing the players squirm can be really entertaining).
What I did was give them all Skills, Abilities, and Equipment associated with their Backgrounds and Races, as well as a small selection based on what Class they wanted to be (Casters got 3 uses of their Cantrips and Warriors got 2 Weapon Proficiencies). For HP I went with the minimum they would have with their class, so 4 + Con Modifier. This is made them nervous.
The adventure took place over the course of 1 night, and they stumbled unto a plot to kill the King (who was a boy). The adventure was a lot more role-play and problem solving oriented, as the players had to figure out whether they were going to try and intervene, go to the authorities, or what. They started off essentially finding one of the would-be Assassins in an alleyway outside of the Tavern they were drinking at, along with a bunch of strange devices and a secret letter. The adventure progressed with the Players using a secret tunnel and navigating some skill checks. "Combat" Encounters were completely avoidable and they did the smart things with the Assassin's tools to avoid fighting the Rats and whatnot in the tunnels. There was a single combat encounter at the end, with 2 False-Guards wanting to kill the boy King and the Players having to hold them off until the real Guards arrived. The Casters got to use their spells here and the Warriors used the makeshift weapons they had picked up along the way.
Overall, I felt the game was super fun. It was only a few hours of gameplay long, but I felt the players had to think more than usual and for that reason I think they came out having a lot more fun (or at least a unique experience).
As a reward (since I did not assign XP), I gave the players the choice of: +1 Ability Point, 1 Proficiency in any Skill or Tool, 2 Languages, or a Favor with the Court. So everyone was able to get something unique that they would not have had a chance to otherwise in a standard game. And that is kind of my take home for running a Commoner-Style adventure, don't make it like a normal game. =)