"Also you will have to take the net income profit and you will allocate the part corresponding to March 27 to December 31. For example, if you have a net profit of 5000 , you divide that by 365 days you will get around 14 dollars per day, so from March 27 to december 31, there are approximately 288 days times 14 you will enter 3945."

For reference:

Note:  The only days that may be taken into account in a taxable year in determining the qualified sick leave equivalent amount for the year are days occurring during the year and during the period beginning on April 1, 2020, and ending on March 31, 2021.

62. How is the “average daily self-employment income” for an eligible self-employed individual calculated? (Updated January 28, 2021)

Average daily self-employment income is an amount equal to the net earnings from self-employment for the taxable year, or prior taxable year, divided by 260.  A taxpayer’s net earnings from self-employment are based on the gross income that he or she derives from the taxpayer’s trade or business minus ordinary and necessary trade or business expenses.

From: https://www.irs.gov/newsroom/special-issues-for-employees

Half-way down, that topic has the SE info.