Connect to your Pi to get to the command line. Then, open the Raspberry Pi configuration tool, better known as
raspi-config, with the following command:
With Localisation Options open you'll be able to choose Change Timezone and select your local timezone.
From the command line, you can simply type
date and confirm the date is displayed in your desired timezone.
pi@raspberrypi:~ $ date Wed 28 Nov 11:10:33 PST 2018