Depends on what you want the airplane to do. Also, if the airplane is a Telemaster and going to be flown like most of those airplanes, you've maybe got about twice the deflection you'll ever use.

What you're doing really isn't going to have pat answers up front. You're simply going to have to flight test and go from the results. Do you have a picture of the airplane? There are a ton of variables that come into play. Like the wingspan. And maybe more important when wondering about aileron effectiveness would be the wing aspect ratio. And it'll still probably come back down to fly and try.

I've got a Sukhoi that'll snap stall with 15degrees of elevator. Fly a buddies 4star that won't stall with 45degrees. Way different airplanes and WAY DIFFERENT safety margins (CG to NP).