It depends upon how detailed you want your model to be
what I have done is place a node at every intersection, then divide up the users according to type resid, com, ind, school, hotel, theater, irrigation ect and look up the billing for a representative of that use. If you have a telemetry system then use that info also.
use common sense for the daily demands pattern such as
classic diural for resid
school start at 7:00 and end at 3:00
theater start at 17:00 and end at 22:00
each demand type can have its own pattern and the base flow can be adjusted to match the quanity at each node
For getting a quanity of users for each node I find an aerial photograph very useful then draw boundries around each node and count or estimate the number of dwellings
I assume you are using 2.0 if not get-it.