Generally, you can only deduct business expenses from business income. You deal with your startup costs in the first year your business is "open" and has income.
Startup costs up to $5,000 can be deducted (with certain limits). Startup costs over $5000 must be amortized over 15 years; startup costs under $5000 can also be amortized if you want to. See here for more https://www.irs.gov/uac/about-publication-535
