After you file

Hi, similar questions as the preceding. If I have a 2017 state refund coming to me in 2020, and I used Schedule A to itemize, do I include that Schedule A tax refund as income on my 2018 return which I'm working on now (3/19/2020), or my 2020 tax return because that's when the IRS and State will have received my 2017 tax return and paid my 2017 state and Fed refund? Thank you.