Wife became self-employed in January, file in September?

Hi all,

 

My wife just began work as a missionary at January of this year.

 

Due to my ignorance, I thought she could file her income tax at the end of the year like everyone else.

 

Should she file her quarterly self employment tax in September because I missed the April and June deadlines?

 

Should I wait til another date?

 

Her earnings are pretty small, about $750 per month which she gets as many small monthly donations from individual people— $25, $40, $100, $20, etc.

 

From January 2019 to the present, she has earned a total of about $6406.

 

please let me know when to file, thank you so much!!!