Bloom's been on Domino for some time, it's reasonable to asmuse that the some time is the space between season 4 and the movie; there are weeks or months that most likely have occured between the two. The events of Bloom's some time on Domino and the events of Season 4 could not have overlapped if they did, Bloom would have had to disappear completely for some episodes, which Rainbow wouldn't do.Tons of movie series have empty time occur between the separate films; most often events that occur over that time are briefly mentioned during the film itself. I'd say this is the most likely approach Rainbow will take.Plus, the whole point of Season 4 was all about Roxy and the Earth Fairies and Rainbow warming viewers up to the possibility of a new character and on a side-note, the Winx earning Believix. You couldn't possibly have had Season 4 occur on Domino or anywhere in the magic dimension if the focus was on Roxy, the last Earth Fairy.