It is extremely common to be very nervous, excited, or anxious going into a race, let alone your first race.
Everyone deals with this in different ways.
Some do what you’re searching for and find a distraction.
Others like myself plan and prepare and spend that energy trying to account for every possibly scenario. I used to pack and repack, check my bike and recheck it, charge everything twice, etc. This is the @Nate_Pearson methodology
I’ve outgrown this a bit by simply having enough races done that I no longer get that much nervous energy ahead of a race, but I still do a lot more prep work
I’d recommend you try to figure out why you are nervous and face it head on instead of finding a distraction. Are you nervous because of the pressure you’re putting on yourself to win? Remind yourself that this is your first race and it’s a learning experience. Are you nervous because of the potential of not finishing? Same as above - it is a learning experience.
There are a myriad of reasons people feel these nerves - it helps me to identify which is keeping me up at night and then figure out how I will mitigate them
If that doesn’t work for you - keep busy (mentally if not physically) by watching a TV show, checking some things off your house work list, whatever. Be a shark, never stop or you’ll die