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 series, meaning that form wouldn't be able to carry over into the timeline, making it placable almost anywhere during/after S4.

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

I choose to ignore all 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 and Roxy was confident with her magic and had her wings. There's no explanation for why the Winx didn't live at Love & Pet, though. I really liked that they did in the WOW comics, meaning that the Fairy Pets and the Winx's adventures in S4 aren't entirely forgotten, but that's besides the point.

Or, this could just be an alternate universe entirely.