It is great that you want to get some practice and some experience. There are a few things to remember though before you jump in, especially without a certification. What insurance are you going to carry? Most personal trainers have insurance that covers their practice. Will you be able to get insurance without a certification? What happens if someone does get hurt and you are not yet certified?
With that being said, don’t let that stop you from getting some experience. Have you spoken to other trainers and asked if they would mentor you? You might be able to follow them for some of their sessions to see how they facilitate a session. You could also ask them to take you on as a client so you could gain experience from a client’s perspective. This is always helpful when you have clients of your own! You could also ask a friend or family member if you could train them for some experience. You wouldn’t charge them, but you could practice what you were learning.
Good luck with your exam!