Mishnah Berurah — משנה ברורה

And tied etc. - Meaning, [in general] if one made a set of windings and also a knot after the wound section, even one knot, he has fulfilled his obligation on a Torah level, even if he didn't make the knot that's closest to the corner. And therefore, [in our case where he did all that before he cut the ends of the strings] it is [considered a transgression of] "You shall make, and not from that which is [already] made". But if he didn't make the knot after the wound section, even if he made the first knot that's before the wound section, [it's considered like] he didn't yet complete the making of the ציצית, because without the knot [the comes after the wound section], the wound section can't remain [in place] at all and [so] you don't have a גדיל/tassel here [which is a requirement]. And therefore, you could cut the strings [in that case]. And there are those who are stringent, and [so] ideally it is proper to heed their opinion. And know, that this that he (ie. the Mechaber) wrote "one knot", he means to say from the five knots that we are accustomed to make. But [a knot that's referred to here,] it is one that is [tied] two times, one on top of the other, as is mentioned below, for without that it's not called a knot since it's not permanent.