If you're asking exactly where along the sketch curve the text is positioned, then you have to adjust your sketch segment accordingly. The sketch text will start at the beginning of the segment. If that isn't what you are asking then maybe you should reword your question.
battle, in a sketch draw the curve with lines, arcs or splines. If there are multiple segments select all of them first. Then type the text and position with the aligning tools - right, middle, left, full justify, flip, etc. Edit or dimension the segments to precisely locate the text.