I agree kabz, but my question really only applies to when you're being radar vectored.
If you are vectored onto final, you're dead on the localizer BUT you're, say 15 nm out from the IAF, can you still descend according to the profile?
I never really had this problem back in europe because they wouldn't vector us that far out, so basically we would follow the vectors, receive our approach clearance and then when within half-scale deflection or 5 deg. we would consider ourselves established and descend in accordance with the profile.