29 days I think, or 30. I don't remember if they give you an extra day after the final bracket. The easiest way to rank up is play Shootout Showdown. You score one goal, end game, send score and repeat. You can play it 762 times a day (the max). 29 * 762 = 22098. That's all-star in 1.5 hours a day.
That sounds so incredibly draining I'll give it a shot though