Originally Posted by
Bloodhound
I can't answer with a reference but as far as I know, you have to join at an IAF. Many arcs are there for a reason, i.e. terrain. Think if you just randomly joined an arc previous to the published point and ran in a big rock.
I could be wrong, though.
If you joined previous to the published arc, you're not on the approach. If you follow the min altitudes, you should be safe anywhere between the IAF and FAF. You could easily come in at or above the MSA and descend on a published portion of the approach if you had the distance to do so.