@sweetmilk
There has been at least one special event in which you could pre-buy a particular month's cards with a SEC as a reward.
There is currently the Advent Calendar which allows you to pre-buy the first 24 cards of this month with another SEC added as a reward at Christmas.
There is also the auto-buy option which will buy all new cards as they are released until you either run out of credits or disable the option. You could use this to effectively pre-purchase as many cards as you want.
There was also the recent lottery where one of the prizes was all of next year's cards, but you had to be very very lucky to win that - and in any case that event has finished.
But in none of these cases do you get the cards before they are released, except for the Advent Calendar where you get them one day early.