To add to what Ante says, if you sing the triads before you play it root: do mi so, 1st inv: mi so do, 2nd inv: so do mi, then after a while you will know where the mi (3rd) is and you can just alter your major triad so mi goes down 1/2 step and then you have the minor triad. Same for diminished and augmented.
But Tomo recommends that we first learn major triads for one key on the top 3 strings (GBE), then next set of 3 strings (DGB), next ADG, and finally EAD. From there you can learn the other keys and after that minor.
So that way you don't get information overload and get frustrated. One new concept at a time, and if you struggle, go back a step and stay there until it is easy. It is natural for us to want to charge ahead because we think you understand and want to make progress, but it slows us down and makes us frustrated if we go too fast.