The best place to start the Tokyo Revengers manga is the very first chapter. It sets the stage for everything that follows and allows you to immerse yourself in the world without missing any crucial details or character developments.
I'd suggest beginning at the beginning. Start with Chapter 1 to get the full experience and understand the characters and plot as they were originally intended. Some people might recommend starting from a later point if they think you're familiar with similar manga styles, but for a complete understanding, it's best to start from the start.