A site reliability engineer (SRE) has responsibility for improving the reliability of an environment by reducing toil, prioritizing knowledge management, striking a balance between operability and functionality, and defining and measuring key metrics. A new SRE must gather the necessary insights on the processes of the enterprise and the customers it serves and review past documented knowledge. In this report, we outline the key activities that a new SRE should complete during their first 90 days, and we reference relevant Forrester research to help ease the transition and accelerate success.