The level? Honestly, I don't remember finishing Fallout 1 below 18, ever. The first time I played it, I was kind of curious of how many claws will I have to kill for them to actually disappear, and I got a few xp. And then I learned that you can get Sniper at 18. And I've always played and killed the deathclaws until I got to it. Then went for the Master.
As for FO 2, it's usually around 30, actually. Hard not to get all those xp unless you're playing stupid or avoiding experience deliberately. In the Enclave there's a lot of experience to reap, I always end up killing everyone in there... oops, Cassidy, why the hell did you have to follow me and Vic here.