Lower Timing modes are normally used for Inrunners, and higher for Outrunners.

You should start with the lower timing, and measure the amp & watt draw.

If you still have plenty of overhead, before hitting the motor's rated limit, even at full throttle, you could try to up the timing ( as you have an Outrunner ), and measure the draw again.

Higher timing tends to draw more current, but if too much can burn up your motor & ESC.