When to pick Blackcurrants

Just a little question,

How do you know when to pick your blackcurrants?
I had 4 bushes on the old plot, yet when i picked them they were black on the outside but clear on the inside and smelled quite bad.
When left to fall off the bush as i didn't think much too them, i found they had become black/red inside and smelled good but if i wanted any i had to pick them from the floor.

Am i missing something or did i have a poor variety?

How do you know when to pick?

Stage 1 ? 

Black on the outside and clear inside  

(crossed over here   :blink: )