Many times sellers ask if they should shut off the utilities (gas, electric, phone, etc) when listing a home.  Others ask if they should turn everything off when they move out.  Some situations require individual review, but for the most part, sellers should NOT turn off any utilities (other than the phone service) until the close of escrow or soon after.  The seller has certain obligations to the buyer allowing them to do inspections, verify things are working as they were when the first viewed the home and to keep up on maintenance. 

Often times, discontinuing electrical service will also disable the sprinkler timer.  During a hot California summer, this can kill a yard in just a few days.  Since the seller is obligated to keep the home in similar condition as to when it was first viewed, having a dead lawn can cause problems even resulting in the transaction being canceled.

So, I think the best advice is to keep the services on until the date the buyer is to take possession of the home.  This way, the seller avoids creating problems that may result in problems down the road.  To determine what is best for your situation, you should consult your real estate professional.