First name on flight tickets...?

For an internal US flight with a US pport, it likely won't be much of a problem right now. It is always best to have your name match exactly what is on your ID when you are traveling. If you are going on any international flights, always have the name exactly as the pports read, middle name/initial as well. Beginning in the fall, US customs will be imposing even stricter guidelines for flights, for security reasons. It's best to get in the practice of it now, even though it may not be mandatory.