User blog comment:Aphrodite Sweetheart/Official Winx Club WOW and 4th movie discussion blog/@comment-31892545-20170609032209

I wonder, if to eliminate the questions about where WOW fits in the timeline, the Winx will lose their Dreamix/Onyrix power at the end of the season, raising just as many questions as the opening scene did: not many, as they weren't seen in a Fairy form, and it could've been placed almost anywhere on the timeline.

We'd still have to factor in/ignore other factors, but the transformation is the biggest timeline hole, besides the "Roxy-knows-the-Winx" thing.

I choose to ignore the factors and place it after S7 until proven otherwise, but i wonder if it takes place sometime after S4E13, when the Wizards went into hiding.