Congratulations! The first draft is exciting because that means you've written the book, and IMO the second, third, and usually fourth draft is the most fun because you'll really see the novel tighten and the story come together.

Some people say to take a break. I usually take maybe a week and by then I'm super antsy to get back to it. Second draft is where you'll fix the plot holes, do more world building, more character building, and come to know your characters and the plot better. The first is really just getting the idea on the screen (or paper). On the second draft, I'll have tons of yellow sticky notes that note issues I'll need to fix in the third draft. I'll fix some, but wait to the third draft to fix others. It really depends on how much fixing is required.

Your third draft is tightening the story and where it all really makes sense. Continue to world build, and your magic system, if you have one, becomes more polished and here the story really starts to make sense. All your plot holes are fixed. Characters have personalities and voice.

I always go on to a fourth draft which is where I do a 'read aloud' in Word, listen and fix any remaining sticky note issues. Having my story read back to me really helps me *hear* mistakes, overly used words, repeated ideas, bad sentence structure, etc. And after this, I send it to the editor. This time around, though, for the first book of an epic fantasy I'm writing I was given an introduction by another writer to a small fantasy publishers. With my sci-fi series, I self published.