You must prorate. There is no deduction for time spent using the property for personal use.
There are three scenarios. One is that you were living in the home as a personal primary residence and converted to rental use. In this example, you would begin taking expenses on the date it was placed in service. You place property in service in a rental activity when it is ready and
available for a specific use in that activity.
The second is vacation home. Here, you intermittently use the home for personal use when it is not being rented.
https://www.irs.gov/taxtopics/tc415.html
The third is a not-for-profit rental. You rent it for less than you could on the open market.
https://www.irs.gov/taxtopics/tc415.html
