Time Zone Configuration
From Koha Wiki
Koha has the ability of handling timezones on a per-instance basis (since [https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=20123 version 18.05). This means that a single Koha server can support instances in several time zones simultaneously!
Set an instance's timezone on creation time
It is possible to set a specific timezone for a Koha instance when it is created. This is done using the --timezone option switch.
$ sudo koha-create --create-db --timezone America/Argentina/Cordoba instance
Manually setting an intance's time zone
To set the time zone for an instance, first find the designation for your time zone from the List of tz database time zones.
Next, edit the koha-conf.xml file for that instance, and add a <timezone> block within the <config> block in the file.
<config> <timezone>Antarctica/South_Pole</timezone> ... </config>
Checking the effective timezone
You can check what timezone is effectively being used by your Koha, by browsing to the About section, in the System information tab. It will display the effective timezone being used, and where it picked it.
When setting up cronjobs, it is important to adjust the cronjob time based on the server's local time. For example, if you server's local time is +5 UTC, but the instance's timezone is in +3 UTC, a cronjob meant to run a midnight for the instance will need to be set to run at 22:00 on the server.
For ease of configuration, you may want to set the server's local time to "Etc/GMT" ( e.g. UTC+0 ).