I have personally know them take up to 12 years for a difficult case.
Any half decent PHYSIO will tell you not to claim for two years as it will often get worse up to this point.
Physio report is nice but pointless as it carries so little weight, it shouldn't but it does in the real world.
Best report by a hell of a long way is A+E consultant, more to do with perception than anything else, but that is my experience.
tabetha