Usually, rental real estate is used in a profit seeking manner. It is entered on Schedule E. In order, for it to be Schedule C, you would have to offer services along with the rental of the property, such as a bed an breakfast or a motel would.
You will have to indicate that this is a multi-family/multi-unit, at least for 2020, so you can segregate your personal expenses from the business portion.
You can't take any expenses for the time period when it was not available to be rented, due to improvements. Your improvements will be added to the basis of the property and depreciated.
