I got confirmation from ETS that the “MyBest Scores” section will be added to all score reports, regardless of when the test was taken. That means if you took the test anytime after August 1 2017, the “MyBest Scores” section WILL be added… as long as you order a new report (which you will pay for, of course). Just keep in mind that the section will only include scores from AFTER August 1, 2017. Also keep in mind that you should order the new report After August 1.
Here’s what they told me:
“Regardless of the test administration date, all TOEFL iBT score reports sent after August 1, 2019, will automatically include the test taker’s MyBest scores, in addition to the traditional scores from the selected test date. ETS will release detailed information to test takers before the new feature is officially launched.”