After you file

You do not "file" a self-employment  tax return mid-year.  But you can pay estimated quarterly tax directly to the IRS if you expect to owe at tax time and and are worried about an underpayment penalty.  Your actual tax return is filed during the tax season, as usual.

Are you new to working as an independent contractor?

https://ttlc.intuit.com/questions/2903027-how-do-i-report-income-from-self-employment

https://ttlc.intuit.com/questions/1901110-do-i-need-to-make-estimated-tax-payments-to-the-irs

https://ttlc.intuit.com/community/self-employed/help/what-is-the-self-employment-tax/00/25922

https://ttlc.intuit.com/questions/1901340-where-do-i-enter-schedule-c

https://ttlc.intuit.com/questions/3398950-what-self-employed-expenses-can-i-deduct

https://www.calcxml.com/calculators/self-employment-tax-calculator     (non-TT site)

https://ttlc.intuit.com/questions/2902389-why-am-i-paying-self-employment-tax