Part-time yoga teacher

I retired last year and began teaching yoga several times each month, making approximately $150-$200 per month, but I'm also paying occasional costs for continuing education and other requirements related to teaching yoga.  My only other income is interest from money market accounts, which is currently $500-$600 per month.  I have not paid any taxes yet this year.  Do I need to make quarterly payments, or can I wait until filing taxes next year?