I'd recommend beginning at the beginning. That way, you don't miss any important plot points or character developments. The early chapters do a great job of pulling you into the story.
The obvious choice is to start at the very beginning. It gives you a clear understanding of the world and characters without any confusion. Plus, you won't miss out on any important details or backstory that might enhance your reading experience later on.
The best place to start reading Jujutsu Kaisen manga is the first issue. This way, you'll experience the story as the creator intended and won't be confused by jumping in at a random point.
Some online manga stores or dedicated manga apps might have the continuation of Jujutsu Kaisen. But make sure to use legal and authorized sources to support the creators. For example, Viz Media sometimes has the updated chapters for you to enjoy.