Adding 7lbs. should put your CYA reading at about 45ppm which would be a good level. Then, you shouldn't need to add any more this year. Sometimes it degrades over winter and you have to add more the following year, sometimes not. You'll just have to wait and see. I will tell you this --- when it does degrade into ammonia over the winter, it often causes a HUGE chlorine demand upon opening. As in gallons and gallons and gallons and gallons of bleach before the chlorine level will hold. We have MANY threads on this forum where people are currently in the midst of clearing up this huge chlorine demand. There is no definitive way to keep this from happening, but the later you can close and the earlier you can open gives you the best chance of not having this happen.

You are right that for now, you want to keep your chlorine at 10-12. Continue to do so until you can go from sundown one evening until within 2 hours of sunrise the next day without losing more than 1ppm of chlorine and your CC reading is no more than 0.5. Then, you can let the chlorine drift down and keep it between 3-6ppm.

By the way, have you read the lowering alk page linked in my sig below and also the one about using muriatic acid? If not, please do so.