Would be good to get indiehackers sharing what channels worked for them early on.
The hardest part is generating traffic for the very initial traction, which can take months of experimenting to figure out.
Being a developer first makes this even harder.
For a previous product I worked on, the sub-reddit posts really helped get some early users. The sub-reddit /r/productivity brought in about 500 free sign-ups from a few posts.
It's a slow road and the current product I'm working on has very few sign-ups. Have started blogging so we'll see how long that takes to pick up on search engines.