Carlos--
If I had a month of un-obligated time to practice, and get ready for a structured course of study such as Guitar Fundamentals, there's one thing I'd be sure to incorporate: chromatic finger exercises. (You may know them as "spider leg exercises.") Every practice session would start with them, and most practice sessions during that month would concentrate a great deal, sometimes even solely, on them. There would be quite a few days where I would do nothing but those exercises.
I'd start with the most basic, one-finger-per-fret, 1-2-3-4 pattern, up and down the neck, on each string, slowly and deliberately, making sure each note sounds cleanly, using alternate picking. When I could do that one fairly well, I'd mix up the fingering: 1-3-2-4...4-3-2-1...2-3-1-4, or about a million other variations I'm sure you can think of. Every session, up and down the neck, slowly, deliberatly, cleanly, and alternately picked.
Further on, I'd use those same patterns across adjacent strings, fingering the first two notes on one string and the other two on the one above or below it, up and down the neck, slowly and cleanly. After some time running chromatics over the neck on adjacent strings, I'd do it skipping a string (or two, or three, or four), fingering two (or one, or three) notes on, say, the A string and the other two (or one, or three) on, say, the G or B. Up and down the neck, slow, steady, and clean.
And in my month off, I'd do a lot of this. It won't sound particularly musical. What it will do, though, is help you build hand strength, finger independence, and callouses to help your fingers not hurt. You'll improve your control, and will find your accuracy and dexterity increasing with each passing practice session. Incorporate a metronome or drum track and you can work on your timing too. If you tune up before each practice session--and you absolutely should--hearing the notes while you concentrate on your fingering and picking of them makes for some decent ear training; the more you hear a clean, in-tune note played on a specific string at a specific fret, the faster you'll be able to hear when something's out of whack.
Guitar Fundamentals is a structured process, and you'll get a nice introduction to chords, and the chance to work with them, pretty early the program. You'll get to scales further along, and you'll have a chance to work with them a lot. All that lies ahead.
But if you start doing chormatic exercises now, and you do them regularly, when you get to those chords and scales you'll get there with stronger fingers and hands, and you'll be more accurate, more controlled, and your fingertips will feel a lot better too. So start doing them and keep doing them. There is no finish line.
All my best. Enjoy the journey.
--Matthew