I think the rule is pretty clear on this, below is a link and it answer frequently asked questions:

http://tinyurl.com/b98go8

What is the definition of a first-time home buyer?
The law defines "first-time home buyer" as a buyer who has not owned a principal residence during the three-year period prior to the purchase. For married taxpayers, the law tests the homeownership history of both the home buyer and his/her spouse.

For example, if you have not owned a home in the past three years but your spouse has owned a principal residence, neither you nor your spouse qualifies for the first-time home buyer tax credit. However, unmarried joint purchasers may allocate the credit amount to any buyer who qualifies as a first-time buyer, such as may occur if a parent jointly purchases a home with a son or daughter. Ownership of a vacation home or rental property not used as a principal residence does not disqualify a buyer as a first-time home buyer.

Definitely ask a tax advisor, since it's the IRS that administers the money.

I notice on these boards that many people who perhaps mean well often answer questions they are not credentialled to answer. You want to ask someone who knows the rules rather than has just seen people doing what what you're talking about.

All the best.