We have a little system where they stand on the rug and wait while I go get that days envelope (they can't know where they are or else it'd all be over in one day. Such boys), then we sing Jingle Bells, take a picture, and open it up. They've been super excited about the whole thing, even though some of the envelopes just have a handful of chocolate chips in them for the treat (What?? I didn't want to go out and buy treats, so I had to make do with what we had). Although I scored a ton of Hershey Kisses at the Relief Society Christmas party the other night that they had leftover from the center pieces. As my Grandpa would say, The Lord will provide. :) They'll think they've hit the jackpot when we get to those envelopes.
I'm loving the pictures we've taken everyday (except for day #2 - it's a must that I take the picture in the morning). I think I'll probably use the pictures somehow in next year's advent adventures.