Great question - Lately operates in accordance to your local time zone. In other words, it'll use your computer's local time to schedule!
You won't see the timezones specified in the post calendar and schedules. Just remember that whatever timezone you're in, the posts will adjust to your timezone accordingly, but will always publish at the time you originally scheduled them for! So, if you're traveling between timezones, be mindful when you are scheduling posts to ensure that you are scheduling for the desired timezone.