Not sure if this is the right place, but here goes.
Warming up, have i completely missed how to warm up before the very 1st lesson? Playing the D chord, or are you supposed to start ‘cold’?
I see some posts here that say play chords or a tune, but what if you are an absolute beginner?
Just my 2 cents:
If you are about to have a practice session, you will repeat a certain technique or part multiple times, so I don"t think you need to warm up separately for that.
If you are about to just strum a random song or songs off the cuff, that would seem to be a good warm-up as well.
If you are going to perform for other, probably you already know what you will play and rehearse beforehand, so the warm-up could be running through the relevant chords or phrases of those songs. You may also want to play some scales as well, just to get your hands in “working mode”.
If you’re an absolute beginner I wouldn’t worry too much. Especially if you’re following Justin’s practice routines.