More as a result of luck than judgement I have managed to get beans coming on at different times, rather than all at once. Some of them are ready for picking.
While others are still flowering.
When the bean flowers fade, the embryonic pods stand up vertically.
As they mature, the pods gradually change their posture to a downwards-pointing one
When ready for picking, the pods should be nicely-filled. You should be able to see and feel the individual beans inside the pod. Pick them when they are young and tender. Old, over-mature ones are tough and leathery.
There are generally something between 6 and 10 beans per pod.
It's not all good news though. Here's a photo showing the two main Broad Bean problems: the disease Rust, and the pest Blackfly. I find that unless these are very severe they don't tend to affect the crop very much. They say that to reduce the problem of Blackfly you should pinch out the growing tips - which I have done, but it doesn't seem to have deterred the Blackfly much - they just seem to migrate a bit further down the plant!
You can eat the pinched-out tips of the plants as "greens", though we don't generally do so since at this time of year there are such a lot of other nice greens available - like cabbage and broccoli.
I would say that Broad Beans are probably one of my favourite veg (I have lots of favourites!), and one of the reasons is that they have a relatively short season, which somehow makes them all the more desirable. Things that are always available can get taken for granted. In the UK you can usually only get fresh Broad Beans in the shops from about mid-May to Late-July. Of course, when you grow them yourself the options are greater...