We should get that first update the day of CES I say, so the 5th, then they can show and talk about WP7 on Verizon at the keynote later that day. It makes the best marketing sense to do so.
Then have something else ready for Feb to talk about at MWC and maybe release. MS knows they need to keep it going and frequent updates keeps WP7 in the news.
I agree with this timeline. Like them or hate them, Microsoft knows how to sell things. They knew that letting people beta test Office 2010, or Windows 7, would increase sales. Windows 7 has sold so many units that it almost hurts my brain to think about it. Office 2010 is the same. It's because they have kept it in the news, and near the front of people's minds.
I am a network engineer, but most of my friends are auto mechanics or farmers. Not exactly tech savy folks. They all know what an iPhone is, and sorta know what a Droid is, although they couldn't tell you what makes a Droid a Droid. When I told them that I got a new phone, they all knew, almost instantly, what Windows Phone 7 was. They knew the commercials, and my cousin actually sang "I'm gonna do my sexy dance! WooHoo!" It's pretty incredible, actually.