My opinion .... your goal on any first race should be to finish, feel good, and have fun! This is automatically a personal record (
PR) for you, and your performance will only get better as you continue to run consistently. There is no bad time.
We tend to put pressure on ourselves to make xx time, and risk needless disappointment. A first 5K is a marvellous accomplishment and you should be proud of yourself for training, taking the leap of faith to register, and showing up at the start line! There will always be people that are faster and slower than us, what is important is that you do the best you can, that day -- no matter what the clock says.
Enjoy the process!! Races are great fun!