Kathleen --

That can be a difficult question to answer. It's usually necessary for me to study a company's history to know what the dates cited mean. The date could be any one of the following:

1) organization,
2) acceptance by the governor,
3) departure for first assignment,
3) acceptance by the secretary of war,
4) muster,
5) sworn into service.

All officers and men present on any of these dates would be recorded on roll as such. Officers weren't always sure what date and place to use, so dates used can and do vary. However, it benefited all company members for the date to be as early as possible, since pay was usually reckoned from the date shown on roll.