First play day as a mom? A little help?

Ok, so this is the first play day for the kids, Finally! We got rained out at the last two, and they weren't rescheduled due to other events in the arena. I am super nervous about the kids and horses. We are taking the two older horses to run on, since they are ready, and I really trust them. They don't spook easy, so I think it will be great. Also, Bozo was a barrel horse before we got him, and it turns out Grandma was a pole horse, some barrels. All four kids are gonna ride them at different times. I have it figured out who is riding who, due to experience on the events. I will also ride Bozo, just to give him more practice in the arena. I am not planning on riding Grandma in the events, just let two of the kids ride her. Nothing against the old girl, she is super fast, but I just prefer Bozo. I have our list ready for everything we need to do, from wiping down all the tack, bathing the horses, to making sure we have plenty of ice and water in the cooler. I am just a little nervous about the kids. They all do so well with the patterns and horses, it's just it is the first actual play day they will take part in. Any advice on how to get over the nervousness? Any pointers about kids running events? I ran barrels as a kid, then roped and team penned as well, starting it all when I was 9, so I remember how much fun it was. I still have fun with it all. That's why I am going to ride, not just practice for the horse! Thanks!