One of the things I realised after shipping my app, was that almost everything I was worried about before the launch was completely irrelevant. It's quite nice being in a bubble and just continuing to make something you like working on, I actually really miss that feeling, but the reality is most of what you make will have to change as soon as people use it.
Before shipping, I had no sense of how large the landscape was and how much noise there is - the trickiest part for me was getting people to see it.
It took a long time. I think I could have launched about a year sooner, but wanted everything to be perfect, which seems a bit ridiculous now. I think it was the realisation that all the work would sort of be for nothing unless I launched it - that made me actually do it.
The most useful initial feedback was from a reddit group (r/testflight), but friends and family gave very helpful feedback too. I just tried to show anyone I could, it was also very helpful to watch how people use it without guiding them. The most useful feedback will feel brutal initially.
After launch, I did a ShowHN on here, which after posting a few times eventually picked up. Press was tricky initially, but after a lot of persistence, there were a few articles too. I had no idea how much work promoting something would be.
Before shipping, I had no sense of how large the landscape was and how much noise there is - the trickiest part for me was getting people to see it.