If you're buying after a loss, it's 31 days after the sale (that produced a loss) to repurchase.
Do you know if you include the date of the sale or if the start date is the day after the sale? That really isn't precisely specified anywhere in the Code or Regs that I can find (just not within "30 days"), but I include the day of the sale and every other example and hypo seems to do the same.
