Firstly you’ll need to know your timezone and/or country, a list can be found in /usr/share/zoneinfo/
The more generic procedure to change the timezone is to create a symlink to file /etc/localtime
# ln -sf /usr/share/zoneinfo/America/Sao_Paulo /etc/localtime
OR you can copy and replace the current localtime setting
# cp /usr/share/zoneinfo/America/Sao_Paulo /etc/localtime
To verify that your timezone is changed use the date command:
# date
http://www.how2centos.com/centos-change-timezone/