Cucumbers - when do you pick?

[workhorse]

This is, I expect a silly question, but as its my first year of growing, and the only cucumbers that I have seen are in a supermarket. So the question is: how do you know when to pick cucumbers?

[Capsid]

When they look like those in the supermarket, but picking them smaller (~6" long) is fine.

[Matt.]

Pick them when you want them!!

Often its nice to pick smaller fruit as they can have better taste. I've found that with the cucumers I've grown before as outdoor types can sometimes get a thick and bitter skin the longer they are left on the plant. If you cut the skins off this doesn't matter as much but even so I'm convinced they taste better earlier. Also the more you cut the more the plant will keep producing.