> With a feeler gauge, check the gap between the bottom of the string and the top of the 8th fret
Feeler gauges are not necessary, it's easy enough to judge relief clearence by tapping the string down and seeing/feeling how far it moves, and go by 'credit card thickness' or whatever.
These are just rough starting points so it's pointless being precise about it or measuring anything. You will inevitably need to adjust everything away from the recommendations according to your needs and technique.
Neck relief should be adjusted such that fret buzz becomes equally unlikely along the whole length of the string, when played by you, that's the optimum curvature.
Each saddle should be lowered until there's too much fret buzz, then raised very gradually until you're happy.
Fret buzz determines a good setup, it has nothing to do with measuring or precise distances.
my bass was taken to a tech when I bought it, than another couple of times for little adjustments, so I always kept things in order. I just want to learn how to do a basic setup
So it will already be at a good starting point.
Setting up a bass has nothing to do with measuring and adjusting things to precise measurements, Fender's guide is for a rough starting point, it is not for a good setup. The document is poorly titled, note they write:
> Modifications of the specs may also be made (within limited parameters) to adjust for your individual playing style or application (i.e., how hard you pick, finger, slap, pop or fret the bass).
Note: These are minimum specifications that are meant as a guide; they should not be construed as hard and fast rules, as we realize that every player's subjective requirements often differ.
In fact, modifications of the specs 'should' be made, always. The stated specs will be optimum only for a very few players, they are very probably not optimum for you.