If you have all Named User CALs, you'll be fine. You can assign manually and let the remainder be assigned dynamically.
The 24hrs is how long the CAL is Quarantined. Basically, if your ran out of CALs, you could only delete CALs that have not been used in the last 24hrs.
Also, QS will not remove any of the CALs, if you need to free some up, you'll have to do it via the QMC.
Hope that helps,