Safety is key. Most of the Safety Officers are 100% comfortable with new IDPA shooters. They want you and everyone else to be safe, want you to be challenged, and want you enjoy your first experience so you come back.
This a laminated card I carry in my range bag of the "IDPA Official Range Commands" taken directly from the Rule Book.
These are the commands you will hear from the SO (Safety Officer) who most likely will be the closet person to you. There is usually an Assistant SO with you also. So basically, you will have two sets of eyes on you helping you and everyone else stay safe.
This is the "B" side of the index card. These are NOT Rules, but just a few "Definitions" and personal interpretations.
Sometimes during online discussions like these, you will hear lots of different acronyms, which can get confusing. For example, "Compooky" mentioned "DQ". Sorry, but it doesn't stand for Dairy Queen. It's a "Disqualification" that is bad enough that your match day is over and you will be asked to leave. There are other less severe penalties, all with their own "acronyms". You might want to download and go through the manual to get the full actual meaning. The manual is actually not bad, pretty straightforward and not overly long.
IDPA Rulebook
Equipment. Again, the rule book will explain what is acceptable and permitted. I know you mentioned your gun is a P320 X5 Legion (O.K. I'm jealous). Confirm you have the correct and are comfortable with your holster, enough magazines, magazine carrier, gun belt, cover garment, eyes, ears, and such. Oh yea, bring ammo.
When is your first match? A lot of IDPA matches have practice sessions on a separate day before the match. I'd suggest going to one to "get your feet wet".
Another idea is to offer to help in setup and tear down. Usually more hands are always welcome, as some of stages require many moving parts. Nothing wrong with getting your hands dirty. Plus, it builds character... so I've heard.
When your squad goes to a new stage , the Safety Officer will go over the COF ( Course of Fire). I.E. where you start, where you can go, etc. If you don't understand a certain part, ask them to drill into a little more.
After a shooter is done shooting and the Safety Officer has declared the range safe, there is always a need to tape up the targets for the next shooter. This is another area were working as a team within a squad makes for a more enjoyable experience. Whatever you do, DON'T TAPE UP THE HOLES UNTIL AFTER THE SO has scored the target. Make sure the SO acknowledges to you that they have scored the target. Also, and this is just what I was instructed to do, if you are the next shooter, don't tape up the previous shooters targets. Let the others in your squad do it. As you are the next shooter, you want to save those few extra seconds or minutes to relax and be ready when the SO calls you to the line. I don't think that's an official rule, just what I do.
Make sure you update this post with your experience.
Enjoy, ask questions, and be safe. And congratulations on "getting out of your comfort zone".
These are just my thoughts, YMMV,
Jay