The best way to see if you've got it right to to fly it!
Enough right thrust and you won't do horrible torque rolls or snap left at full power. Enough down, you won't "balloon" or nose up/stall. Generally, one or two degrees is enough for small slow/park flyers. If a kit designer specifies "x" amount, that's always a good place to start- you'd hope he's done a test flight or two himself! Fly it, get it trimmed for straight and level, and see what it does when you hit the power hard. Adjust from there if needed.
Hope this helps,