When exactly did he contribute?  When exactly was it converted?

If a person contributes between January 1st and April 15th, they can contribute to the prior year. 

For example, let's say March 2021 they decided to contribute $6000 for tax year 2020, and $6000 for tax year 2021.  That would be fine.  Well, except that the $6000 for tax year 2020 should be on the 2020 tax return.