Hot hot is your spa water? I suspect it may not be at 104ºF if you are soaking up to an hour. Also, I'd be surprised if two people soaking that long would have the chlorine level not get close to 0 within 24 hours. If you are still measuring FC, then OK, but with your bather load it would normally take more chlorine. Are you using the spa every day?
You shouldn't need to test for CYA. Just keep track of how much chlorine you are adding. For every 10 ppm FC added by Dichlor, it will increase CYA by 6 ppm. How large is your spa in gallons?
You should probably get a handle on using Dichlor before you switch over to using bleach. Before you use bleach you need to get your TA much lower (closer to 50 ppm) and add 50 ppm borates (most easily done using boric acid). Since this is a new spa for you then you might just use the Dichlor-only method that is simpler, though you'll need to change the water sooner compared to the Dichlor-then-bleach method. With a new spa the water won't last as long the first time anyway especially if you didn't purge it first (using Ahh-Some).