That's good planning. Go to the section for "sale of assets and other things" on the income page, and report the sale of the home. Use "my home" for the type of asset. I believe the program has a smart worksheet that will guide you to enter adjustments to the purchase price (cost basis) and selling price. (If not, enter the adjusted cost basis when the program asks you for purchase price.)
When finished, the program should say something like, "you qualify for the exclusion and you don't need to report this sale or pay tax." but give you some check boxes for alternative situations, and there should be a check box for "I want to pay tax and not use the exclusion".
