How many sprinklers your system can run at one time depends on how much your home can supply. Your flow rate will determine the total number of pop-up sprinklers you can use at any one time. Different pop-up sprinklers will have their own flow rate. Similarly, drip lines contain emitters which distribute water at a certain rate (typically 2 l/h). The bucket test will also tell you just how much drip line you can run on one zone.
An easy way to calculate your flow rate is by doing a bucket test. All you need is your garden tap, a standard 9 litre bucket and a stopwatch. Before you start, make sure you measure your water flow at times of peak water usage. If using a tap timer or pressure reducer, make sure you measure the flow with the device fitted.