Likewise, you should not approach a distributor immediately upon their return from a market. They have been out of the office for two weeks, have a lot of messages to return, and a lot of paperwork to process from the last market. The best time to approach a distributor is 60-90 days before a major market. Assuming a distributor wants to acquire your film, it may take 30 days or more to negotiate a deal. You should have a distribution agreement finalized and executed at least one month prior to your first market.
Filmmakers know about film, distributors know about distribution.
Don't kid yourself and think even though you are a novice you can play in the other guy's arena and win. There are many pitfalls to avoid. A good negotiator should be able to improve the terms enough to outweigh the expense of hiring them. An attorney or producer rep who represents many filmmakers may have added clout. The distributor knows the attorney is aware of what the distributor has paid for other films, and the concessions the distributor has been willing to make.