3GX guys needed again, but in my experience with other FBL units: You won't know until you take it up to hover and test it out. This is a Dx6i? Then 70-75 would probably be a good starting point. Dx7s or better, then 50ish is probably good as a starting point. When you hover it, if you notice it isn't holding well, then land and increase 5 points. Repeat until the tail does a fast wag, then back it off a few points at a time until it is steady.