How long after addition of agonist can the wells be read by using the Cell Meter™ No Wash and Probenecid-Free Endpoint Calcium Assay Kit (Cat# 36312)?

I wonder how many wells can be measured in a run, without loss of signal in the last wells distorting a dose curve for example.

The endpoint assay is appropriate to determine the calcium response from a full 96-well plate if the whole plate is read immediately after the addition of the calcium flux stimulant.