This is a corollary to the previous post on the dangers of the writing what you know mentality. If you do choose to write a story based on something from your own personal experience, the closer you are to that moment, the less sense of perspective you have on it.
Think about perspective as being the range of magnification that you can see an event with. When dealing with something that happened five minutes ago, you can only see the situation in close up. You’re able to see the details of that moment, but not the larger context. Compare that experience to something memorable that happened seven years ago. You can still see the close up details of the event, but you can also pull further back to see the chain of cause and effect that lead to and from that moment for you. You can pull further back to see how that moment relates to other, similar moments you may have experienced. You can even see how others involved in that moment have been affected by it, and you may even be able to make assumptions about their motivations and actions while in the moment you’re remembering.
There’s also a process of natural selection that happens to choosing ideas to work with. Every idea seems fantastic when you first have it. Ideas that still seem great months or even years later are ones with staying power. Writing something based on an event that hasn’t had that time to fight it out with competing ideas does a disservice not only to your writing, but the idea. Without giving the idea time to prove its strength and fully ripen, you’re cutting the thought off at the root and freezing it in a state of immature development.
This isn’t to say that an idea based on something that has happened to you recently can’t become a great story, but by giving the inspiring event time to move into the past tense, you allow yourself to detach the idea from the facts of the moment so that you can focus more on its truth. “That’s how it actually happened!” is a weak justification for plotting, but weaving something that did happen into a fictionalized version of events can be a way to make the fictionalized aspects of a story feel more honest and real.
Your duty is to your story, not to your past.