How can I effectively skip periods of time in my story?

Maybe instead of saying next week or a bit later on, try describing a task one of the characters is trying to accomplish, like learning a spelling list, or science project, drivers ed, getting a tan, learning to ride a bike. For example: bla bla bla Joey helps Dana learn to ride her bike she received for Christmas. She was excited all Jan and Feb even though the snowy ground prevented her from even taking it outside. When March finally arrived she and Joey took the bike outside. BANG 2 months ped just like that! Of course, I hope your writing is way better than mine, but you get the idea. Good luck!