A typical pop up sprinkler...full circle, about 3.5 GPM. Half circle = 1.75GPM
Make a trip to a landscape supply. There are many options for you in terms of lower flows.
To determine zone run time, you have to consider the head. The figure you need to know is precipitation rate, which is how many inched of water per minute fall PER SQUARE FOOT of area. Fixed sprays have higher precip rates than a lot of the rotors, so can run for shorter time.