I would not hesitate. Better to give it a go then to regret and wonder. Now I will admit that I grew up on horseback and have shown a lot over the years; but, like others had to transition from one discipline to another. I was amazed at how less stressful showing dressage was compared to hunter/jumpers and even some of the breed shows (heck just having ride times I found to be a Godsend).
Preparation is key to decreasing anxiety. In addition to memorizing your test(s) and practicing on your horse in whatever fashion you feel will yield the best results, I would make a list of everything you’ll need to take with you and have your trailer/truck packed in advance. I generally keep my trailer packed with my show gear with the exception of saddles and bridles. Schooling shows are usually lower key. If you have questions as to what is ‘legal’ call or email the show secretary if your coach can’t answer your questions. I have found most show secretaries to be very helpful. If you can trailer into the location prior to the show that too might help mitigate ‘risks of the unknown’ for both you and your horse.
I took a hiatus from showing for a few years and then jumped back in and was so happy to meet several very helpful and gracious volunteers. Many people recognized me but there were a lot of new faces too who didn’t hesitate to go out of their way to offer assistance especially when they saw I was showing on my own. So, go and have fun and treat it as a learning experience with the only expectation is to go and ‘survive’. If there is any question about the canter then do the walk trot tests for your first go, you can always move up the second show. Having taken many a baby to their first show and project horses, it is best to give them confidence too by not over facing them. Good luck and have fun!