I think he is speaking of his ARF Decathlon?? Was it A Phoenix??? Makes very little difference who makes it though.
You need to know where the datum line is before you can even guess about the incidence, if not then you need to know and trust the incidence that the builder has installed in the wing or stab so you can get the plane set up like steve said so it doesn't move around on you.
So many other things effect how the plane fly's and trims, CG and engine thrust for starters. These are things you can figure out before you borrow an incidence meter.
An incidence meter and incidence is something you really have to learn about before you dive right into it. Try reading up on it in A book or the instruction book if it's A Robart.
I have an old book titled Scale Aircraft by Gordon Whitehead from 1980, published in the UK. It's an old book but you should read it or one like it several times so you have A better understanding of what you are trying to do. I have also built from Mr. Whiteheads plans, the man knows his stuff!! MY copy was A gift and located on Ebay several years ago.
Books, instructions, learning, sort of like school!!