I consider dday a "sentinel event" meaning it has the same type of weight as a death of a close loved one, a rape, or other similar type of event. For me, I started feeling strange about 4-6 weeks prior to the anti-versary.
For the first anti-versary of dday, I was able to take the day off. I had no expectations of getting anything done that day and didn't do anything. I was a crying, blubbering mess and spent most of the day curled up in a ball on my bed.
Second anti-versary, we were separated and on our way to D and the day fell on the weekend. Still, I'd been feeling down about 4-6 weeks prior. I set no expectations for the day. This time, I wasn't a crying, blubbering mess, but I did practice self-care and didn't do much.
I just watch how I'm feeling for about a month before & a month after. I sometimes do feel a little down, but nothing like in the early days.
Do practice self-care. If you want to stay in bed all day, that's fine. If you feel like going out to lunch with a friend or going to get a pedicure, do that. You do what you can to make it through the day, knowing that tomorrow is another day closer to healing.
BW M 34years, Dday 1: March 2018, Dday 2: August 2019, D final 2/25/21