Davab:
The important thing is that you maintain that 5-6” bottom section intact and continuous. As shown in your link, cutting the notches for the treads and risers reduces that 2x14 or 4x14 to an effective 5 or 6” deep beam/stringer, along the bottom of the member, and you don’t want to notch that further. So, most good carpenters make most of the cut with a circle saw into the corner lines and then finish the corner with a hand saw, saber saw or some such, so as not to overcut the reentrant corner. Lay the first stringer out, cut it and check it. Then use it as a template for the other stringers. This assures they are all the same. Watch out for floor finish heights and actual height, fl. to fl. in laying out the first stringer.