String Length

I have a Savannah. I am currently interested in trying a bunch of different strings. One maker has asked me to measure the string by letting it hang from a nail and measure from outside of loop,to the outside of the other. He also said it needs to be the length at the correct brace height before measuring. What if I don`t have a string on the bow currently? How do I order a string?

rule of thumb is to lay the bow down measure from the loop noches down the lenght to the other noch of the bow subtact 4"

The Savannah is an AMO 62" bow, which uses a 58" string, brace height is 6.25-7".

http://www.martinarchery.com/2012/savannah.php