“Pack as if you're going out for only a week during the summer. Then add what you'd need if you were going out for only a week in winter. That should pretty much cover everything.” –MrNoodly1)
“I can't be prepared for everything I can possibly imagine, so I prepare for things that are most likely to happen.” – MrNoodly2)
This section includes items that take a long time to do and/or that are beneficial to you whether or not you choose to live in a van.
This section assumes you are planning to hit the road sooner rather than later. Starting a year out means you can test out your van in all four seasons with your “home base” resources at hand. It also means you can get up to speed on core skills like cooking, laundry, grocery shopping, etc.
On planning your build, roseakamom10 says:
Spend time in your van. Throw a minimal amount of stuff in there and go on a camping trip or even just stay in your driveway but don't go in the house. Think about what you want and need in a build, figure out how you will do things in that space if you couldn't go back in your house. You will learn so much about what will or won't work for you. This will help prevent you from wasting time and money on things that work well for others but won't work for you.11)
On cooking, jimheim says:
Spend the [time before departure] at home practicing. Only cook meals that you'll be able to cook on the road. Limit yourself to the cookware you'll have. If you have to ask, I suspect cooking with these limitations is new to you. Best to learn at home so you're prepared. It'll also help you identify cookware essentials. See how much you can do with limited pots/pans/utensils and no appliances. Get used to living without a fridge and microwave for leftovers. It's a steep learning curve. You can make great food on the road with those limitations, but if you're not prepared, you'll come to dread dinnertime.
This section includes items that are best done while you still are in a physical residence.