Don´t worry too much of adjusting the starting length lower of the [words=https://shop.mattersofsize.com/products/sizegenetics-penis-extender]extender[/words] because of the 1 week lay off. Do like this the first tim you mount it, warmup using a hot wrap,
manually stretch your dick for about 15 min using different exercises.
Then immideately after mount your [words=https://shop.mattersofsize.com/products/sizegenetics-penis-extender]extender[/words], at the same rod length (extender starting length, don´t change it), but don´t screw up the thumbscrews at all in the beginning.
The during every 10 min or so, screw the thumbscrews a little (increase the tension).
Then for each set the first day (you don´t need the manual before now), ease your way up to your former length before the lay off.
You will definitly bea able to reach your former inside the [words=https://shop.mattersofsize.com/products/sizegenetics-penis-extender]extender[/words] length at the end of the first day.
Now, get back to stretching business fella!