Grief-Process and Length? Does it vary?

I lost my older brother almost 2 weeks ago. He was 27 years old and I'm 26. We weren't as close as I wished we were and he died unexpectedly. I haven't been sleeping very much and I'm so sad. I realize that I'm supposed to be upset, but is there a typical time frame that this takes? Will the images of him stop flashing through my head? (I unfortunately saw him dead prior to the coroner's office removing him). Is it typical to want to run away from everything (job, home, breaking up with bf)? Any advice on how to make this process easier?