The details tab of the tournament page is home to key information about the tournament. To navigate there start by going to the tournament page, and then make sure you have selected "Overview" at the top.
From Overview scroll down and make sure that the "Details" tab is selected.
On this tab you will find the game, region, date, time, and Format of the tournament you are currently viewing. If the tournament organizer makes any changes to the date or time then this tab will automatically update to reflect those changes. Note that the region displayed here is the region the tournament is intended to be played in, not necessarily a region lock. Always read the rules of the tournament for full information.
Please also be aware that if you are logged in, and you have set your timezone correctly in your account settings, then you will always see the tournament time in your local time.
Lastly, if the tournament has been region locked by the organizer then the details tab will display different language alerting players to the region lock, including flags and country names of all allowed regions.