I have two pretty distinct memories of getting Bionicle for christmas-
The first was when I received Cahdok and Gahdok. At the time, I though the sets were long gone from store shelves and it was a set I had almost forgotten about. Given how young I was at the time, that was a set that took quite a sizeable amount of time to build, and was really my project throughout the whole day.
My other memory was of Zaktan. A tradition in my family is to open 1 gift on christmas eve, as a way of "getting you through the night" (Nowadays it's a good way to end a christmas eve party). But anyway, when I was young it was usually a new pair of pajamas, but in 2006 my mom threw in Zaktan. It was the first Piraka I had, and to this day 2006 is not only tied as my favorite year for Bionicle alongside 2001, but the Piraka are some of my favorite sets overall. Needless to say, having Zaktan that day was an absolute blast, he was such an awesome start to a new generation of Bionicle sets.
There's certainly other "holidays" that I had fond memories of- for example, getting the large battle of metru nui playset in 2005 for my birthday. Another one is actually ore recently, back in 2014 I was sent the 2015 Bionicle sets early (as documented in my reviews on Eurobricks and cameos on video reviews of the wave on BZP's youtube) which happened to fall around the end of October. I was putting the sets together, talking with my friend over skype on halloween and noticing that it was already snowing outside here in michigan. A great time of year and a great wave of sets.