The first beta version was made available on 10 June, the day of the keynote, and the second came two weeks later, on 24 June.
Now BGR writes that the third beta is scheduled to arrive on July 8.
The report cites sources who had already announced the exact date of the release of iOS 7 Beta 2.
The site writes that this version could bring minor changes to the interface to make it more cohesive.
Apparently, Apple is set on maintaining its two-week release cycle for beta testing releases.