A white board is an invaluable tool for someone with ADHD to begin with. You can quickly jot down notes, you can leave yourself reminders, you can use it to write new ideas on, you can use it to draw explicit images of genitalia 8==D ( . Y . ) hehehe. But no seriously it's great I don't know how I'd get by without one anymore.

In particular something I do every morning is write the date on my whiteboard (yyyy/mm/dd is the superior way to date things) and it's not so much that it helps remind me of what day it is (because it does do that). It's more of just a grounding thing I find like, I feel more grounded throughout my day knowing what the exact date is. When I don't write the dates my days start to bleed into each other and I just don't feel I have as good of a grasp of time when I don't write the date down.

So try it out! I personally think everyone could use a whiteboard to begin with but in particular I think writing the date down every day is a good way to stay connected with the days as you go on through the year.