Get your taxes done using TurboTax

If you are cash based ( not accrual) then all income received during the year is taxed income in that tax year so if they pay you some in 2021 you report it in 2021 even if you have no expenses to report on that job.  It is up to you  to decide what is in your best interest ... seek local assistance in how to set up your books and run a business ... education is key to your success.