Sure would be nice to if all you had to do in life was put up a minimal information post, and things would go as desired.
In lieu of that...
Polling the community for interest before making plans is advisable.
Post an eye catching invite, followed by a well thought out description, and minimal entry response to hold the event.
Advertise on all gaming and coding platforms, and it is helpful to have other admins, of those forums, onboard with the idea. Networking = less working.
Keep a planned date or cancel. If you don't have enough entries to host it, you probably won't have enough entries by rescheduling it, and you'll also lose entries who cannot make it on the new date, as well as aggravate those who have already made plans to attend on the original date.
Make sure you have a few over whatever minimum need to attend, because 100% show is almost impossible in any event.
Now if there really is no minimum, quit with the rescheduling. Just host it for a smaller than anticipated group, and see how it goes. If it's a hit, the next one will be bigger and better. That's just word of mouth advertising, the best free advertising money isn't needed to buy.
Anyway, just my two-cents on event planning. I've put together several large golf tournaments for over 30 years, so I feel my two-cents are worth every penny.
As far as this event goes, I hope it does take place, is just about fun and profits the participants, rather than just giving code away.
Pete