Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

Odd question perhaps but is there any mention in the lore of specific celebration days or occasions, along the line of birthdays/Christmas/independence days or such like?

I never really read the lore but interested in any mention, whether galactic wide or local, Xenos or imperial.

The biggee is the Feast of the Emperor's Ascension, which is basically a Christmas-equivalent in terms of importance in the calendar. There are also loads of saint's days and the like though.

Sanguinala

Depends on whether or not you consider the Regimental Standard to be canon or not.
Generally, there are two big holidays which are Sanguinala, a 40k version of Saturnalia which was used as the basis for the Christian holiday Christmas, and the Feast of the Emperor's Ascension, where people celebrate the Emperor's sacrifice in His ascending the Golden Throne. Apart from that, it depends on which Cult your world adheres to and which Saints it venerates.

Watch the Lord Inquisitor on YT.
There's a really nice procession in there. Not official, but thats how one could imagine it.

If I remember right, one of the SoB novels depicts a local celebration where they basically reenact a miracle done by a saint (including some participants getting killed for added authenticity).