One of the toughest things to endure after the loss of a child ( or any other significant loss) is to get through holidays and other special anniversary dates. Even if you don't remember what the date on the calendar is, it is very likely your body will react in grief. This was one of the most amazing things I experienced after losing Gabe. I would be having a terrible day, crying and so depressed and then later realize that it was an anniversary day.
Now here is the thing. I don't think there is a single answer how to deal effectively with these times. I think it is highly personal based on your personality. I can tell you that it will get easier each year until you can function "normally" during special days.
Here is a link to some articles that may be able to help you ease the pain during these difficult days.