I ended with a reference to your calendar. I recommend some sort of calendar or plan when planting a garden. I found a great reference to use.
After you have picked out your seed, or even during the selection process, put your last and first average frost dates into this and then put in the days to maturity of the seed you are using and it will tell you when to start/plant seeds for your area and if you can have two plantings, spring/fall.
Then you can just write down on a wall calendar or desk calendar when you need to start them. I would also put the frost dates on this as well. Another handy thing to add to a calendar would be daily high and low temperatures. If you are so inclined and have the means, you can add precipitation. For my area, wind is also a consideration.
I would use a desk calendar or a daily journal type calendar for keeping larger amounts of information. A daily journal type calendar would also be handy to keep from year to year for comparison, and to perhaps pass onto another generation in your area.