Adbrew uses the time zone set in your advertising account. You can check your account's time zone at the top of your screen, just beside the account selector dropdown.
To set any rulesets and automations, including dayparting, you can simply set it based on what hour of the day you want it to take place and it will be done based on the account's time zone, regardless of where you make the change from. For example, if you set a ruleset to run at 7 am on an account running on PST while working from Australia, the ruleset will run on 7 am PST and not on 7 am AEDT.