From your messages you've been off the erg for ten years, have never rowed afloat, have shoulder and knee problems and may well be overweight.I'm getting back into serious rowing after a few years.
Effective training plans start with a 2k test, which implies that we know how to row, have no injuries and have at least the endurance to do a 2k at reasonable pace and so set our training paces. Can you do that? If not, suggest a month of 20' increasing to 40' SS at rate 20 and see how it goes, concentrating on stroke quality at least 10W' (Power/Rating).
Then if you can, do the 2k test and set your training paces/powers in proportion. Six months gives you time to do at least another test and so reset paces. However the SK race is just a start. Do not stop again.