If your business was not officially "open for business" in 2019 then you will not report anything concerning this business on your 2019 tax return. Period.
If your business was "in fact" open for business in 2019, then you will report it on SCH C as a part of your personal 1040 tax return. Doesn't matter that you had no income.
All expenses incurred before your official "open for business" date are startup expenses. All expenses incurred after the "open for business" date are business expenses and claimed in the section specifically for business expenses.
Just ignore the questions about income -- do NOT enter zeros.
That's just flat out wrong. If you leave it blank the IRS will assume that you forgot to enter your business income and it's a sure fire way to get audited. If you were "in fact" open for business in 2019 and had no income in 2019, then enter the digit zero for your business income.
Note that with no business income in 2019, it's perfectly possible (and very likely) that not one penny of your business expenses will be deductible - to include your startup expenses. Generally your businses expenses can only be deducted from business income (I say "GENERALLY" as this is not always true.)
So if you have no business income in 2019 to deduct your business expenses from that you paid in 2019, you still "claim" those expenses on the 2019 return. They just will not be "allowed" is all. They will get carried over to the next year where you can deduct them, provided you have the business income to deduct them from.
But if you don't "claim" those expenses on your 2019 tax return, then you can not carry them forward next year to your 2020 tax return.
For startup expenses, that's not a big deal. Startup expenses are deducted in the first year you are officially "Open for business" and it does not matter in what year you incurred those startup expenses either.
You are limited to deducting a maximum of $5000 of startup expenses in your first year of business. Any amount over that is amortized (not capitalized) and deducted (not depreciated) over the next 15 years.
