Apologies for the blogging break. It was not intentional. I biffed off to the mainland on only a few hours' notice to help my sister and her family. They had come down with stomach flu. I helped out for two days, spent day three on the couch with the aforementioned stomach flu, and then promptly caught my nephew's cold. You can't tell a toddler not to cough in your face. Another week of cleaning and cooking and whining (mine) followed. I returned on Wednesday hugely overdosed on Mucinex so I would not cough or sneeze on the plane and bathed in hand sanitizer. I had called the airline to ask if I could move my ticket to this coming Monday, when there would be no chance of passing it to my fellow travelers, and was told by the agent in a fascinating bit of time-travel that she had "looked several weeks out in both directions" and could not find a flight change that would not cost a thousand dollars. Okay, then.
Moving a story through time is something new writers often make more of production of than it deserves. No reader is going to fling your book aside should you start a chapter with "On Monday morning" or "The week before school started." Like the word "said" as a dialogue tag, these are fairly invisible and painless ways of getting from here to there, or from now to then.
Being clear is Priority #1 in all writing if you're not James Joyce or equivalent. Don't get too tricky when moving in time. Don't try to be subtle by mentioning your character's newly-long hair or changing all the classes he's taking or having it start snowing when we think she's sunbathing on a hot day in the back yard. Unless, of course, something has gone drastically wrong with climate change. Make the bones of time clear for your reader.
Once you're moving through time clearly, look at how to do it well. Some writers hang their shingle on knowing how to end a chapter on a cliffhanger, of not wrapping up a moment in time, which forces the reader to keep going to find the closure that never quite arrives in any chapter. See Dan Brown for this. Others are so dextrous and brilliant that they don't have to flow in order with the clock or the calendar (are you listening, American Airlines?). Read Gabriel García Márquez's One Hundred Years of Solitude to see this genius.
Possibly the best lesson in moving through time for any author comes from a genre of literary fiction popular among Serious Male Writers, which I call the Somewhat Interesting Woman's Life Story. These women are usually taken advantage of in their youth or even childhood by men, think they come to terms with it through various relationships which then explode, and only then finally deal with everything, either swearing off men or finally finding The One in middle age, too late for the happiness of which they had early dreamt, but nice enough and on their own terms.
Anyway, I was reading about the third of these novels this year and I was about to fling the thing at several points, but inevitably the author cut the scene, and that part of the tale, within a few pages and leapt into the next misadventure. So there is the final suggestion: jump ahead in time when you can. Especially when the story is shouting "Move along— nothing to see here!"