You must make at or above the 125% poverty guideline level. https://www.uscis.gov/i-864p
If you just meet or are just barely over the 125% poverty guideline level for your household size, you may want to find a joint sponsor as some consulates, especially high fraud consulates, are very harsh on those who don't make well over the minimum guideline. If you make below, you will most definitely need a joint sponsor. Either that or find a better paying job and work for long enough to be able to show pay stubs if you make below/just at the minimum level
Note that even if you have a joint sponsor, you are still required to fill out I864 as you are still the primary sponsor, even if you don't make enough. The question is not whether you are required to fill it out, because you are 100% required to fill it out if you are the petitioner, but rather if you make enough to qualify as the sole sponsor
