In general, your home office deduction can't exceed your home-based business income. Here is an article that will provide more information: Home Office Deduction.
If you were not "open for business" in 2019, you cannot take any deductions for expenses you may have had. Please see this link for more information on Start Up Expenses: Start Up Expenses
Once you were "open for business" you will be able to deduct and/or start to amortize your start up expenses, as well as record your other expenses and your home office expense.