I can't find any sloes, so I make Damson Gin and Damson Vodka. Slightly different flavour from Sloes, and you use more sugar to make Damson liqueurs, I believe.
I've decanted half of it after 4 months (it's delicious) and I'll leave the rest for 12 months this time, to see what happens. If anyone's interested, here's the method, which is the same for both Damsons and Sloes, although Sloes use less sugar, I think. Can anyone confirm, or refute that?

The ratios I use are:
1 lb Damsons.
6 oz sugar.
1 Litre reasonable quality Gin or Vodka.

Prick the Damsons or Sloes well, with a fork, and put them in a sterilised, sealable jar (eg, Kilner jar). Add the Sugar. Add the alcohol. Keep tipping the jar around for a few days until all the sugar is dissolved and distributed.
After 3 or 4 months, decat and strain, preferably through muslin.

You can bake with the boozy, remaining fruit.