Here was the first place I saw the 13th as the date, I think:
Motorola Milestone Update 2.0.1 Termin / Date | Goddchen 's Blog
Nothing sure, but Moto did come right out and say that a service update for the 'stone would drop directly, followed by 2.1 "within the next 2 months". So the 13th is as good a date as any.