It depends on what you want to achieve. Do you want to rapidly build up a community around the project or you just want to provide some value on the long term to whoever may be interested in what you offer.

If you want the former, then you'll probably have to spend considerably more time engaging with users, and, as a developer myself, I can say that that will probably be annoying.

If you want the latter, just let things flow naturally. Periods of development and user engagement will probably alternate, as you spend time working on a new feature and presenting it to the community and gathering feedback.

You may also want to spend a small amount of time daily/weekly to just check on active user feedback.

P.S. I run and NGO and manage/develop a platform consisting of a mobile app and a site that allows users to send feedback to public institutions on various types of problems and also integrate the public info so that it is available for anyone to check out. Personally I want this to evolve organically and I spend my time as described above ( the second scenario ).