If I didn’t write the first novel; I would have no basis for a prelude. This concept seems odd, but the concept of my original novel evolved. I did not begin with a cult, but the idea came early and grew from there. The cult; now, drives the novel. Incidents from the recent past are mentioned, but a prequel expanding on the events sounds interesting.
I began the prequel and the process is easier. Outlining the novel seems feasible this time. One of my posts dismisses the use of outlines, but once you have a formula then an outline is possible. Writing a couple of chapters before the outline still seems to be a good idea. A prequel has an established end and a probable start, so these are the chapters you need in your head before you flesh out the rest.
I will query agents while I write this second book and will hold off on independent publishing. I can’t edit the first novel any further without professional assistance, due to burnout. An agent could give me such assistance, but if my query letters fail, then the prequel will give me a different perspective for a while and may help in perfecting my first novel.