I got a Gardens by the Bay stamp and sent a letter to myself so I could get the post mark. Yes, the stamp is pretty limited and you can see it takes half the length of the envelope.
Since I was sending said letter to myself, I figured it should open it in 2015.
And then I checked my own previous message to myself that I sent in 2002 since I forgot when I was supposed to open it.
16 May 2012.
Well ok.