Metal-Organic Layers (MOLs), 2D analogs of Metal-Organic Frameworks (MOFs), feature monolayer structures with the potential for various applications. Controlling the lateral size of MOLs is essential for enhancing their dispersibility in solvents and optimizing performance. However, reducing lateral dimensions while preserving monolayer thickness presents a challenge due to the precise conditions required for monolayer formation. This study utilizes a time-resolved solvothermal synthesis method, employing flow chemistry to adjust reaction conditions dynamically during different stages of MOL growth. Fast nucleation is triggered initially to generate numerous nuclei, followed by a shift to slower growth rates, limiting further expansion and preventing the formation of amorphous structures. This approach effectively refines the lateral dimensions of nano-MOLs while maintaining monolayer integrity. The reduction in lateral dimensions has a direct effect on improving catalytic performance, demonstrating the potential for fine-tuned nanosized MOLs in advanced applications.