What do I put as my start date for a new business? I started investing money into a new business in 2021, but did not make any income until 2022. What should I put?

To clarify why it's hard for me to put an exact date, this is for rental income. I'm now a landlord, and started investing money into fixing up my home while I still lived there in 2021. Finally in early 2022 I moved out, and started receiving rental income. Would the first date be on the first day I spent money on fixing up my home?