This morning I listened (again) to a really good IndieHackers podcast with Laura Roeder where she answers this question (thanks Courtland!). Her suggestion was to buy traffic from Facebook, IG, etc. at the beginning. Once you're seeded with some regular visitors, continue to work on getting more organic traffic coming in.

But like everything, 90% of success is showing up, so first you actually have to tell people the blog exists and post stuff!