I am still working on my first publication, but this is the current plan:
Intro Chapter ~1,000 words
Main branch: 10x ~1,000 words (I wanted to have enough to get people interested and keep people interested)
Major side branches: 3 x ~1,000 words (1 intro chapter each)
Worldbuilding: Complete (my story currently has 6 chapters introducing the world and various races...yours may not need this)
I also have enough extra chapters for one chapter per week for a year, approximately 1,000 words each, so that I don't feel pressured when I'm unproductive. Though most of the chapters are my creations, I have a co-creator who is adamant that we should flesh out at least one of the side branches pre-publication, which means I'll probably be closer to two years of content in the queue prior to publication.
I don't like a million tiny branches that don't go anywhere. My main branch is expected to be at least 50, probably closer to 100, chapters in length. Branches off the main branch will be intended to reconnect to the main branch, so that they are not left dangling, never going anywhere.