The first thing you should decide is exactly how much meal planning you want to do, in regards to how many days or weeks to plan ahead of time. This really depends on you and a number of factors should be considered. Think about how much time you have for meal planning and prepping, how often your family likes to switch up recipes, and realistically what you can spend at the supermarket for planning these meals.
You should also consider how much room you have in your refrigerator and freezer. Planning for 3 weeks ahead of time is fine for the schedule, but you might not be buying food for this long if you don’t have somewhere to put everything.
When you are just starting out, try to plan for just one full week and see how it goes. This should include all meals and snacks your family will eat for that entire week, including breakfast, lunch, dinner, snacks, and desserts.
It includes meals you will prepare at home with leftovers, lunches your kids and you will bring to work or school, and any extra items you need, such as bringing brownies to the local potluck or any other special occasions.