To be considered for a P visa, you should be a non-immigrant who is seeking entry to the US either as an entertainer or an athlete. You need to apply for a P visa long before your performance is required at the US-based event, to allow for delays in processing your application.
If you are able to secure a contract for your performance, you should indicate in detail the dates when your performance is required. This will be the basis for the length of time your P visa is valid. Your employer must be prepared to shoulder the cost of returning you to your home country should your contract be terminated before the due date (assuming you do not get a P visa renewal.)
You will get a P visa if you also have a residence in your home country or other countries aside from the US which you intend to return to. You may find that you qualify for a P visa renewal if you already had a P1, P2 or P3 visa granted before. If you are a dependent of a P visa holder, you may also seek P visa renewal.