You do this within the state interviews of Turbo Tax. The Business tab prepares the federal Schedule C, and does not address state allocations. In the event of being a part-year resident of 2 or more states, numerous federal items would need to be allocated within the state portion of the program or website.
Every state is a little different so far as how it approaches business income and the information it requires, so you may have state-specific questions as you go through the questions. Some states will merely ask for a net income (loss) attributable to that state, requiring just a single figure, while others will require a more detailed accounting of the allocation.
We are happy to address any specific questions/ concerns as you navigate through this process.