Hey, it’s completely fine to decide you aren’t ready yet! In fact, I admire that you’re willing to say that. It shows a lot of maturity, in my opinion.
I’ve definitely been in this position (I’m actually in it now, to be honest) and I think stewing on it for a couple months or a couple of years is the best course of action. For me, it’s a massive historical fiction project that I’ve been sitting on for five or so years now. I’ve spent my time fleshing out my characters, researching, plotting, getting inspired and that sort of thing.
Since you’re writing a fantasy, I’d focus on a lot of worldbuilding, since that’s an aspect that often takes years to develop. But also don’t be afraid to work on other things. Short stories, poetry, smaller-scale novels, or whatever it is you like doing. If it’s a story that really matters to you, it’s going to stick around for however long it needs to 🙂
Mahalo keia huiʻana