While following a strict rigid schedule might not seem like the best way to let the creative juices of film making flow there are some times when it is absolutely essential to have a schedule. Just realize, the number of people working on a film can vary greatly and could range from just a small set of dates reserved for the filming process up to an entire set of shooting schedules that is broken down into hour increments. The choice is yours in how you decide to lay out the schedule, but creating the schedule is very important to successfully shooting a feature film.
Just imagine the chaos that could ensue if you were simply calling up actors the day you wanted to start shooting. You would likely find that it is very difficult to actually get all of the actors that you need, exactly when you needed them. The larger your cast is, the harder it becomes trying to locate everyone at the same time. However, if you have a rough schedule created in advance such as when you are doing the initial casting you would be able to let everyone know when they would be needed which could be a huge help in trying to rearrange their own personal schedules. Just imagine the hassle of having an entire cast minus our main character when you are ready to shoot only to find that they were not given the schedule in advance.
Sticking to the schedule down to the minute is certainly not necessary. If you find that you work best under those conditions it is acceptable and entirely up to you. However, breaking down into a schedule that at least has day part and day laid out is helpful to cast. Not everyone is able to devote every day for a month to a video, especially if they are not being paid. Using volunteers or actors that are working for extremely cheap wages means you really need to take into account the schedules of others in order to have actors willing to work with you again.
There are occasions when it is virtually impossible to start scheduling shoots in advance, for example if you really need a natural rainstorm you should let the cast know this upfront. Keep in constant contact with people when rain is expected and ensure that everyone knows as far in advance as possible. It nothing else, if your cast knows you are in search of rain they may contact you at the first sight of rain to make it much easier to locate everyone.
It is best to always have a schedule available as quickly as possible for cast members to refer to as well. If there are any changes that need to be made, these should also be passed along quickly. A cast is not going to enjoy working with you if you fail to ensure they are informed about the important issues such as the schedule in advance. Just continuously think about how you would feel if you were the person left out in the dark on the schedule, you likely would not enjoy it. Showing your cast a bit of professional courtesy can also go a very long way towards having people talking and saying good things about you.
Often this professional courtesy of an advanced schedule will be able to extend into other benefits as well. Actors are notorious for talking, if they talk to other actors about how much they love working with you and why, you should see an increased turn out at your future auditions for films. This can make the selection process much harder ultimately, but will certainly provide the benefit of giving you plenty of actors to choose from, and a much more advanced set of actors to choose from. Just remember, this is another area where practice makes perfect. Be willing to make a few mistakes and take responsibility for them, the cast and crew will notice and appreciate your approach.