I've just finished this years batch of sloe gin: only a single bottle, sadly. One should not pick sloes until after the first frost, and while we did have a light frost at the beginning of September, it wasn't really enough. Some harvest as soon as the berries appear ready, freezing them to similate the frost, but in my experience that creates a second rate drink, because the timing is to do with ripeness as much as frost breaking down the fruit.
So we've left it as late as possible, and a little later still. We got around 2lb of berries that are now happily steeping in around 6oz of sugar and 75cl of a decent London gin. Expected drinking time around Aug-Sept 2015.