(Leaving a large enough blank like to write in whatever dates are needed.)
I would also put down how much the photographer paid the person.
The point for any contract should be to make a document that both parties can use as a reference so that they know "who" is responsible for "what" and "when."
Should either party have a question, they have something to refer to.
Contracts are meant to keep people OUT OF trouble but so many people seem to use contracts as if they were setting a trap for somebody.