It's tough setting all flying stabs.

Paul's sketch is a good starting place. But take note of the fact that if the wing has a lot of built in incidence then the elevator WILL look like it's trimmed too far down. The old Hobie Hawk is a prime example of this.

I also suggest you do some run testing with the model. Hold it over your head with a light thumb and two finger grip at the balance point so it sits level in your light grip. Then run into the wind and feel for the model wanting to try to pitch up or down. If you run fast enough or the wind is strong enough the model should feel lighter in your grip than when still but not try to lift out of your grip. Adjust the elevator trim and re-test until it feels like that. Once set it's time for the first high start launch or proper test glide into the proverbial tall grass.

I've done a number of models that way now and it's gotten me close enough to the proper setting that the first test flights only needed a few clicks of trim either way and totally avoided any heart wrenching surprises.