This is my summer routine for lesson planning: Before school gets out, I compile ideas of new things I want to try. In the past I've allowed myself to purchase a few teacher idea books, usually Mailbox. However, this year I've discovered Teachers Pay Teachers http://www.teacherspayteachers.com/ so I bought some things from there. I decide on my themes for the year, and I print off blank lesson planning sheets. These are just what I use during summer planning.
After school gets out, I write the themes and dates on the sheets, blacking out holidays and other changes in our schedule. As I'm sure you do, I keep my lesson plan books from year to year and use them to plan. I plug in books, small group lessons, large group lessons, and activities for center time. I always leave some out that I'm tired of, didn't go well, etc. In those holes I put new ideas. All this usually takes me a couple of weeks.
Once I've decided what activities I'm going to use, I organize them by weeks. To do this, I use crates with hanging file folders. I have two folders in each hanging folder: activities and copies. I have 5 crates for the year, 36-38 weeks, depending on the year. I number the crates and also label them with the weeks they contain so it is easy to find things. All this takes me about another week.
After I get all this organized, I go through each week and make notes on what I have to do to get ready. I'll make games and posters, etc. This takes another couple of weeks, depending on how many activities I reuse from year to year.
After I have completed this, I go through each week and complete a To Do/To Collect sheet. I put this sheet in front of the lesson plan sheet for each week in my lesson plan binder. This way, on Fridays I can see what I need to do or collect for the upcoming week. I try to do as much as I can ahead of time in the summer, but some things have to be done right before.
This is my way of keeping my sanity throughout the school year. I am a busy mother of three boys and planning lessons and getting all the hands-on activities ready each week was just too much for me. Even just finding them in my black hole preschool basement is more than I have time for each weekend. So I work in the summer to keep my sanity during the school year. But I'm done. With my lesson planning.