Where did Tully meet Dawn before the resort at San Pedro?

It turns out that Tully already knew Dawn from Wyoming. Thelma Barston is Dawn's stepmother, and after they bought the ranch where Tully worked in Wyoming, Dawn developed quite a crush on Tully. The only time he ever spoke to the sixteen-year-old Dawn was when she rode up to his trailer one day and he called her an "Annie Oakley in Polo."