After you measure the gauge on the SWATCH you've made, compare your gauge to the gauge given for the pattern you want to make.
If it's the same, you're IN! Knit on!
If it's smaller, go up one needle size.
If it's larger, go down one needle size.
Re-swatch to be sure!
This will save you sooo... much time in the long run, if I could, I'd make the swatch for you!