Last year they went on sale in late August.
During the first 2 weeks of the month during the week, you can usually get a standby seat by getting in line 30 to 45 minutes ahead of time. Weekends and closer to Christmas are a longer wait. If you are going to have a nice dinner anyway, I would go with the package. We have done it twice at LeCellier and the cost of the package is about the same as the dinner, plus you get the reserved seats and the 15% shopping discount.