Don't worry about that. Just stick it in there and go. The hole saw will find it's own center to some degree. I did mine with a 2 1/8" and they came out great.

I wondered why the frisbee was getting bigger......and then it hit me. '05 BA - Mulberry/Graphite,128 mains,42 pilots,TBS needles,drilled slides,debaffled stock pipes,Uni,no snorkel