I've had the same spa for 11 months now. I'd recommend only putting 4 cups of salt in to start even though the book recommends 7-8. My dealer recommended this and I can see why. Over time the various chemicals added are sodium based and so is your sweat. The salt values will creep up so you just want enough salt for your salt meter to read OK (it will be in the 7-8 o'clock position - you'll understand when you see your touch controller).
Biggest advice I have is the first fill will be a PITA to control the water. Due to leftover stale water from factory testing the first fill is tough to control water sanitation. Don't be afraid to use it for a few weeks, get a feel for it, and if the water is challenging to keep sanitized don't be afraid to dump a cup of dichlor in, let it run for an hour, then drain and start over. I battled my water for the first 2-3 months until I got fed up. Water care has been a breeze ever since my first re-fill.