Shims with Rega and Benz Micro?

I am about to set up a Benz Micro Glider on my Rega P5. Do I need to shim the tonearm? If so, how much? with the tapered arm of the Rega it is hard to tell if it is level.
Thanks for the help.
4mm is a good starting point. I use 4 with my current Glider (SM with MR stylus). I used to have another SM Glider that had the FG-S stylus and it sounded best with 5mm.