[BadgerDog]

Looking through the archives, I've come up with a simple pattern that leads up to the release of each HQ.

The number of days next to the event represents how many days after a full scale cog invasion is announced.

Cog Invasion Contest Is Announced. (0 Days)
Cog Invasion Begins. (Aprox. 3 Days)
Cog Invasion Ends. (Aprox. 5 Days)
Cog Invasion Winners Are Announced. (Aprox. 38 Days)
Front Page News Says Cog HQ Is Coming. (Aprox. 68 Days)
Cog HQ Is Released. (Aprox. 98 Days)

Judging by this pattern, I'd say that Bossbot HQ will be released somewhere around March 23.

Again we come back to around the same date as all the other HQs were released on.

Sellbot HQ: December 19, 2003.
Cashbot HQ: February 17, 2005.
Lawbot HQ: April 25, 2006.