In TurboTax, there is separate entry for Start Up Costs in the Business Expenses section.  Once general information and self-employment income is reported, you will arrive at the business expenses section.  Select Start up costs - you will be asked to enter your total startup cost, and the date incurred (which should be before you started your business). Then, the program will ask you how much you'd like to deduct; the rest is automatically amortized for you.

You can elect to deduct up to $5,000 of start-up costs and amortize the remainder over 180 months, beginning with the tax year the business begins. The deduction of $5000 will be listed as “other expenses”, whereas the amortization will be reported as your depreciation.