We got a lot of free formula from the hospital! But we did have to use some formula early on with Charlie, and then we switched him to formula after 9 months. I think we bought some fairly soon after we got home from the hospital.
Olive has been ebf so far, so we haven't bought any for her. Once we do transition her, we may just go straight to cow's milk or hemp milk. I say "may" because this is just my speculation... Mrs. Bee is a lot more informed than me on this stuff.
How long after your LO's birth did you buy formula?