I decided to stitch-hack my initials into the sample jumper.
Rather than use charted letters from an external resource, I used the computer to put the text into a range of fonts and sizes. I cut them out and placed them in the position I'd chosen, to find the right size:
Next, I used an online tool to create a sheet of graph paper at the same gauge as my fabric, and traced my chosen text onto it. I included some rows of plain stocking stitch between the letters and the opened row.
I tried on the jumper and basted a line to show the position: