Correct on the salt...
Keep up with the water changes but make sure to try and keep the salt content at 0.3%, it is vitally important to vacuum the substrate daily and keep the temp high, you can get rid of the ich within a week doing this.
After you notice the last cyst drop off, keep the treatment going for 7 days after that. If you notice no re-occurance after that period then lower the temp back to your "normal" running temperature and continue with your regular water changes. A little salt in the water will prevent any ich from coming back and will be gradually removed over time with your water changes.
Try as well to reduce feeding a bit, you need to keep the water quality high during treatment, the fish with the raised temperature will be slightly more hungry. Resist the temptation to overfeed. They will be totally fine not eating as much.
Best of luck and hope everything works out well.
If after say 7 days the salt is not showing any signs of treating it or it is getting worse then get a bottle of ich medication and follow the instructions on the bottle EXACTLY.