I planted my first garden this year and have been having a blast watching everything grow so far and I was out watering today and found thy my green beans have already started to produce! It seemed like yesterday there were they were pretty pink flowers haha.
I'd say the one on the right looks pretty close for harvesting, though you could probably leave it another day or two. My general rule is I pick them when they're as long as the distance between my thumb and pinky when outstretched (gently, not as far apart as they can go), but obviously hand sizes vary!