I understand your concerns, but if they didn't think you were qualified to work charge they wouldn't put you in that position even though it appears there is a need for you to do so. Being in charge means that you are responsible to "supervise" or "observe" other caregivers. It doesn't necessarily mean that you are legally responsible for their actions. It also doesn't mean that you should "know everything." At the very least you should be a good resource and know where to help them find the answers if you yourself cannot help or answer them. That may mean knowing which policy manual to look in, or to call the administrative manager on duty if needed. Other departments of course too can be a good resource when in doubt such as calling one of the intensive care units for advice etc. Staff are more nervous these days to take on that role, but to tell you the truth I don't think there ever is the perfect time. Everyone feels unsure at first. Many of your senior staff members may remember working charge right out of nursing school. As I stated prior, someone must identify good decision making skills in you or you would not have been approached to be a charge nurse. Be confident, stay calm, and a sense of humor never hurts either. Good luck!