When setting times for triggers and sends, these times will be in the time zone that is set in your profile in 'Admin > Containers & Users' and then find the user's profile:

For more information on time zones in triggers see the below article:

https://support.vutu.re/hc/en-us/articles/360020557257-Sending-an-email-on-a-specified-date-time-using-a-Date-Trigger

For more information on editing a user's profile, see the below article:

https://support.vutu.re/hc/en-us/articles/360020555457-Managing-your-user-accounts-Create-Edit-etc-