I'd show up with a W&B done, performace done, weather printed out, notams, TFR's etc. I hand it to him for review. I don't like to be charged $50/hr to have someone watch me do something I can do at home. I would also show up having studied and reviewed airspace, FAR's, AIM, WX, etc. Most people I give BFR's to are weak in emergency procedures. Scary weak. Review those as best you can. You can't practice them at home, but you can metally prepare for them.