+Timing = More RPMs, Less Torque, higher Amp draw
-Timing = Less Rpms, More Torque, less AmpDraw.
When determing the best timing point, the objective is to have the best combination of those three components. Most motors usually are pre-adjusted at the factory (particularly the hand-wound Mods), so the best bet is usually to try and keep the factory settings. If you can't be exact, the range Sosidge suggested is a good guestimate