How to calculate fair rental use days if tenant pays some months rent late in following year

Hi - I have a rental property that was rented out for the fully year of 2019. However, there were 3 months that my tenant paid rent late in the following year in 2020 so I won't report those 3 months rental income until I file 2020 returns next year. However for calculating the fair rental use days would I still use 365 days since my tenant was living in this unit for the full 2019 but a few months rent was paid late in 2020?

 

Thanks!