I say, why not? Probably not for the 40 days of Lent, of course, because that's kind of the whole point of Mardi Gras, but the rest of the time, why not?
Actually, Mardi Gras, is technically only one day: Mardi=Tuesday and Gras=Fat or Grease. So Mardi Gras is Fat Tuesday, but Carnival is the season from Epiphany (January 6) up until Ash Wednesday.
I say if the Christmas decorations can go up in the stores the day after Halloween (in other words, All Saints Day), then I can certainly start Mardi Gras a little early.
Year-Round Carnival Scarf
Yarn: Yarn Bee Special Effects
Amount: Every bit of one skein, including splitting the plies to eke out the fringe.
Needles: Size 11
CO 20 stitches
Knit for 12 rows then begin pattern
Pattern : Beginning with a knit row, work in stockinette for nine rows. Beginning on the tenth row (the purl side), knit three rows.
Repeat pattern stitch until you have 12 pattern sections, then garter stitch for 8 rows and cast off. If any yarn remains make fringe.
Notes: This scarf will curl a bit, though not as much as it would without the garter rows. Still, this yarn wants to be knitted in stockinette to show off its varied textures.