When is it the right time to sell?

Back in my younger days I was a huge lego collector and fortunately I have stored each of my sets with their original instructions. A friend of mine brought it to my attention that a lot of my Star Wars set are probably worth something. I've been doing some research and it looks like most of my sets have seen a price increase since when I purchased them. Now most of my sets had been purchased between the years of 2004-2011. My question is when should I sell these sets? Have their prices plateaued or are they going to continue to increase? Will their prices decrease if I hold on to them too long? I would love to hear from some input from more experienced lego sellers!