I just re-read about the Tuesday pool party - perhaps you should wait until after the party to shock. In that case, pour 5 jugs 8.25% and be ready to add more. Test FC/CC twice daily (early morning and evening). Add bleach as needed to keep FC at 15. If it drops below 8, test / dose more often. FYI each jug of 8.25% bleach will add about 3ppm FC to your pool.

Don't add any more tabs to chlorinator.

I just noticed that you pH is a little low - Add a box of Borax (20-Mule Team - laundry aid). You won't get accurate pH readings while FC > 10.

Keep us posted.

P.S. Why do you cover the pool at night?