Trying to stay with the keep it simple idea.

If the FC levels are marginally OK before the pool party they won't be afterward.
If you leave it that way for a while, you'll get to see CC climb.

Also with marginal levels, if you pump goes off for a long time, the sun beats on one end of the pool then the FC levels drop. Then, even when the circulation is restored, there might not be enough FC to convert the CC and finish the process.

So the real levels are important but lack of circulation can sneak up on you and start the build up of CC.

If you know that loading in the pool is the trigger and you monitor how much junk goes in and guess about how many kids do not leave the pool when they should, you'll stay out of trouble by knowing you need to pour in an extra gallon or add a few hours if your running an SWG.,