At what lvl could you start reading

The main hurdle for reading will be learning basic grammar (you don’t need to understand it deeply, just have a vague notion at first). It’s also worth knowing a lot of common vocabulary, so you feel like you’re almost able to keep your head above the water when you start reading.

In the beginning, you probably won’t be reading so much as deciphering. It won’t feel like reading until you’ve made your way through enough native material.

Alongside the options @polv mentioned, if you wanted to try to jump into manga and see how it goes, I recommend looking into the Absolute Beginner Book Club. Whether it’s joining the next upcoming club, or reading something the club previously read, you get discussion threads with questions and answers that can help you understand the grammar and vocabulary lists to ease looking up unknown words.