Sentinel selection begins in the fall of each year with open applications. The most qualified applicants are selected to try out. Formal training starts in mid-January, 19 weeks before Memorial Day weekend, with Zero-Day, a daylong training session where the candidates will be assessed in physical fitness, ability to learn and adapt, and desire to excel. Candidates who complete Zero-Day are designated Sentinels in Training and will return the following day to begin working on skills such as marching and rifle dill that are critical to performing at the Memorial Day ceremonies, as well as continuing to improve their physical fitness. 

Training will continue with three-hour sessions twice each week until Memorial Day. At this point, each trainee will have devoted approximately 140 hours to team training, as well as countless hours working at home. Unfortunately, some will suffer the disappointment of not being selected. A maximum of 12 are chosen, and many times less than 12 meet the requirements to serve.