It's important that your account's Timezone and Date Format match those of the region in which you're sending and receiving messages. These settings affect features that require date & time values, such as campaigns, triggers that fire on a schedule and anything operating on an @date variable.
To edit your account's Timezone and Date Format, first navigate to your account page and click the organization icon to edit organizational settings.
Then, select the appropriate Timezone and Date Format from their corresponding drop-down menus. If you plan to collect date & time values from your contacts, it's best to choose the most widely-used format in your region.