Here's my novel writing routine:

Thoroughly plan the novel between July and December (plot outlines, research, character profiles, and so on).

Write the first draft (from a thorough outline) between January and April the following year.

Leave the manuscript aside for one year. Revisit it a year later and prepare a revised second draft. Only at this point do I send it to a small amount of trusted beta readers. Then, I revise and revise again as needed, using fresh beta readers, until I eventually have a version ready to send to agents and publishers (after the final version goes through an editor, I might add).

Normally, at this point I fail to secure publication (I've come damn close a few times to mainstream publication, having had a variety of agents, but I did manage to get three of my novels published via a small indie publisher, although I made less with those than my self-published novels).

If no one bites, self-publish (ideally with people in place to write early reviews and whatnot). Publicise the book as best I can, as creatively as I can, across my various platforms.

Rinse and repeat.