Special depreciation allowance for 2024 tax year

I read the IRS document regarding special depreciation allowances for the 2024 tax year.  Is it concerning items in the 2024 tax year only?  Our rental started getting used 06/01/2023 so it's first year of being a rental goes into 2024. Does the special depreciation allowance only concern things that started use in the 2024 tax year? I am unsure if they mean calendar year (first year of use) or tax year only?