It is important to point out, since you did not note the timezone with that quote, that the launch is actually scheduled for NET 07:26am EDT or 11:26:00 UTC.
You can get live countdowns and updates at https://www.spacex.com/launches which will link to first-party livestream coverage during the launch.
No need to go through third-party and advertising-laden dot-com sites.
The Falcon 9 and Falcon Heavy are intolerant to countdown holds late in the sequence. In particular, after propellant has been loaded, there must be no delay in launch. Any countdown holds will necessarily turn into a scrub for the day, as the propellant must be completely unloaded and the process restarted to prepare for launch. With the instantaneous window, it'll either be "go/no-go" at 07:26am EDT, or they'll go-around to another opportunity on Monday morning, around 07:22am.
The timezone has no bearing on the the one minute wide window. This was not posted as an advertisement of launch time. I provided the link the info was taken. If you click on it, it shows you the localized time. Not really sure why you feel like this was the important part of the question.