I have seen it both ways, you have to strike a happy medium.
I have seen people enter an IDPA match who are barely qualified to operate the mechanics of their guns.
On the other hand, I have heard and read people to say "I need to get ready, maybe I can get to a match next year."
It would be nice if everybody could get training so that they would be safe and effective from the start, but that is not likely. Said training is either expensive enough to discourage many or it is offered by the same volunteer labor that puts on the matches. Those volunteers only have so much time and energy to support the sport and training is not as frequent as it would have to be to catch all the beginners.
It is up to the shooter to study and practice the requirements of his chosen event so he can be safe and not interfere with proceedings. But don't while your life away "getting ready." Get out there and test yourself and see what you need to learn and practice. If you pay attention and stay active, helping out around the range, you will get plenty of help and advice.