I am waiting for a confirmation before buying the calendar.
You can Wait till December 24th, to purchase the Calendar and still get the SEC card for Free.
Any December 2nd through December 24th cards that you have purchased Prior, will be deducted from the Price of the Calendar.
So you can buy the cards 1 by 1, up till the 24th, and then purchase the Calendar for the Price of any remaining cards, and still get the SEC for Free.
Just make sure you make the purchase before it ends on the 24th.
To Be sure, maybe you will Purchase it on the 23rd.
Last Year I had internet issues and missed out on the last day because I couldn't connect.
So it is better to not wait till the last minute..