I find that my stories evolve as I write them and as readers respond to them. For me the most important thing is having the core characters and their dynamics. I know what I want the dynamics to be between these characters but the events, the plot develops as I write. I always have lots of interactions planned out in a list which I add to in an unpublished chapter. These are the main events in my story which help with planning its direction. I released my current story as soon as I had written the introduction, but I knew exactly where I wanted to go with it over the next few chapters and they were written very quickly. I have several unpublished stories which I won't be so quick to release. I add to these as and when I have time. I would say just go for it and let your writing develop organically, don't over think it and enjoy writing. There isn't a right or wrong way to do it.
