Personally, I wouldn't use the shock with the extra stuff in it. Just my $.02. It is OK to use the trichlor as long, as you noted, that you monitor your CYA level. Also, remember that trichlor is very acidic and will drop your pH level a lot so you'll have to monitor that closely as well. What is your prediction for when the pool will be up and running? I hope not too far away so you'll get lots of time to use it this summer.