Turning A Novel Into A Screenplay

I have a media relations client that would like to convert one of his novels into a screenplay. I have identified a writer that is interested in writing the script. My question is, how does this type of deal usually work? After a legal document has been drawn up indicating an agreed upon compensation by both parties, does the author (my client) and writer get paid after the script has been sold? Or, are fees typically involved before the project starts.

This is totally new territory for me -- so any insight given will be greatly appreciated.

Thank you.

NOTE: I do plan on consulting an attorney on this matter, however, I wanted some feedback in order to know the right questions to ask.

Some years ago one of my novels was optioned by a writer/producer. I signed an option agreement negotiated by my literary agent, and I was paid on a quarterly basis over the development period when a director and talent were attached. When the major investor backed out, the checks stopped and the option became null and void.

The screenwriter would have been paid once we were out of development and preproduction and into shooting. Until then he was working on a wing and a prayer.

However, this was all due to the fact that the writer was also the producer. What you should do is contact a reputable entertainment attorney and work up a standard contract with an option amount and schedule built into it.