When I worked in advertising in the mid 90's and on, we planned and produced campaigns about six months prior to its release in media on the market. This together with consideration of seasons and competitors, enabled us to finish on time. In order to do so, the easiest way is to calculate estimate time backwards. Here is an example:
Pretend that you want to write a book. What do you then need to do? Your list might include things like:
* Do research about the subject
* Write an outline
* Write three chapters per week
* Take a photo for the cover
* Edit the content after having it proofread
* Turn it in for print
* Present it at a function or fair
How do you get this done on time? Start by setting the deadline and think of the last thing you need to do. Then ask and calculate how long this will take for you and your partners/co-workers, suppliers, clients etc. Add a little bit of cushion for any unforeseen delays such as technical difficulties or waiting time as well as time to process the pieces in the creative process to satisfaction. Mark this done in your calendar when you need to begin this step.
What step is done right before turning it in for print? Proofreading is. How long does that take? With experience (or ask an editor) an hour per page is an average for each project to completion. Then you have a deadline for this part of the steps.
Before this you want to take a photo for your cover. When, where and who will take it? Another date in your planner perhaps two weeks prior to handing it in for proofreading.
Mark each task this way and you will soon have an overview of your goal to write a book, given that you know what to write, for whom and why.
Now get to work! And adjust accordingly by becoming aware of the conditions you need for your best performance and take care of those first, with a little reward and follow up weekly or daily.
This type of time management planning can be tried with start-ups, webpages, movies, music, dance performances or even baking a cake. Have fun (and don't forget to jot down all the ideas you come up with as you start planning)!