Just a couple of items to consider:
I'm within a month of graduating my first hens to freezer camp. They've reduced egg production from 2.5 to 2.0 eggs/day for my three girls in their third year, so you might consider giving yours an extra year. I thought two years at first, but I'm not running a tight-margin factory farm, so I can afford to keep them even when production drops a little.
I've purchased a killing cone and got some training/experience on how to humanely process chickens. If you haven't done it before, you should see about getting some experience first. Not everyone can handle it.