The major scale is the benchmark of all "western" music and much of world music. The major scale will be our "ruler" for evaluating chords, keys, chord progressions, etc. A true understanding of this scale both backwards and forwards will quicken your understanding of the NNS. Since we're thinking in intervals (whole, whole, half, whole, whole, whole, half), we don't have to memorize what keys have sharps/flats etc. Everything becomes "relative."
Please make sure that you're able to create linear (across one string) major scales for ANY note. You want to be able to do this for both open and fretted notes. Make sure you can do this quickly, both backwards and forwards. This will truly help your understanding as we proceed through the course.
Remember again that we're talking about intervals, so don't get confused if you identify a note as a sharp or flat (example: F#). When thinking about this relative world of music, we don't have to be constantly thinking about the musical alphabet and sharps/flats. In time, this will start feeling very natural to you.