For a sole proprietorship or single member LLC which is reported on SCH C of your personal tax return (including a joint return) you don't file the SCH C or report anything, until the first tax year the business is open for business. While I still recommend seeking professional services if you've not got the experience and/or knowledge in this, make sure the person you pay for their services teaches you, and doesn't just "do" it for you without you knowing the intricate details of what's going on when it comes to taxes. If they're not willing to share their knowledge, then why pay for it.
For a SCH C business, all expenses incurred prior to the official open for business date, are called startup expenses. For most many of these expenses are not deducted per-se. Instead they are amortized over the first 15 years of the business. Some expenses may actually be business assets. Those are capitalized and depreciated over time. What gets amortized and what gets capitalized depends on the nature and type of startup expense.
