Start the SLAM process....now, keeping FC levels at SLAM level as often as possible. As long as you follow the guidelines for proper chlorine levels during the SLAM process, it's safe to swim as far as the chlorine level is concerned. (Please reference the articles in Pool School).
That will kill the algae and prevent new algae growth, but won't clear the soon-to-be dead algae already clouding your pool. Once you've SLAM'd for a few hours, you should start to find dead algae accumulating on the floor of the pool. If you absolutely need to have the clearest water possible by tomorrow, my suggestion (along with the SLAM) is to start vacuuming the dead algae to waste, replacing water as needed. Run the filter 24/7. If you have a sand filter, adding the right amount of DE will help (please don't add it while vacuuming to waste!).
If it was my pool, I'd check the CC levels before allowing anyone in the pool. If CC's are in check, FC is at or below SLAM level, and the water looks ok (doesn't have to be CRYSTAL clear but you want to be able to see the bottom of the pool for safety reasons), then you are good to go. But by all means, continue SLAM process until the water is crystal clear and you pass the overnight test.
