petty theft first offense in california. what can i expect on my court date?

The fact that you have no prior record will definitely be a factor in your favor. Your first court appearance is called your arraignment, meaning the court wants to know whether you want to plead guilty/no contest or not guilty. If you cannot afford an attorney, the judge will appoint one to you on that day. If you would like to hire an attorney and you haven't done so by that date, then the court will usually give you some time to find an attorney.

At your first court date, your attorney will get the complaint (what you're charged with), look at the evidence against you, review it with you and advise you of your minimum and maximum penalties, as well as your rights and other consequences.

PC 488 is petty theft but if there is any evidence that suggests you had the intent to steal prior to entering the store, you could also be looking at a commercial burglary charge (PC 459). Again, you will be advised of all the charges at your arraignment.