Should you learn scales first and then the triads? And I'm assuming you also need full knowledge of the fretboard before scales. I'm assuming you need to learn scales first, since you need to know the 3rd and 5th of every scale to make a major triad.
In practice, you'll be learning them both together. The way GW seems to work, at least for me, is you start with C major, learn the intervals, learn the layout of the fretboard, string by string, one at a time, and then the triads for each string set. Wash rinse repeat for the next key. Before you know it, you've learned the fretboard.
The early lessons focus on just a few common keys, so learn them as you encounter them in the lessons. There's no need to memorize a scale dictionary first, map them all onto the fretboard, THEN go back and apply diatonic triads to it. Use small cycles, learn the key center, learn the intervals, learn the triads. (with a heaping helping of learning songwriting chords and strumming in-between!)
Then the lessons in Foundation and Technique and Music Theory I will extend everything from there and you're on your way.
Ah, I see. But still, there's something I don't quite get. When you say "then learn the triads for each string set" which triads are you referring to? The triads for the I, IV and V chords of the scale? The triads for every degree in the scale?
Don't over think it when following the lessons.
For starters, just do the root of the scale. In C Major. Learn C triads Root position, 1rst inversion, 2nd inversion, as Tomo instructs. String sets 123, 234, 345, 456. Then follow the lessons. And keep building.
You'll learn to convert major to minor triads pretty early. Then you'll learn to make the major and minor triads in all inversion for simple blues, jazz blues chords, 1625 chords and other songwriting chords. And you'll want to experiment with string sets, mixing inversions for different sounds and more economical movements.
As you study the theory and foundation lessons, you'll map out the rest of the diatonic triads along the way. But simple major and minor triads cover a lot of the ground and help you get those interval and relationships burned in. do mi sol, mi, sol, do , sol do mi -- 135, 351, 513. You'll say it in your sleep eventually!
Start at the beginning, work through each lesson and add a little bit with each one. Keep notes, review daily, if possible.