When do Jerusalem Artichokes Flower?

[cardinalflower]

I planted mine ages ago (thanks to A4A members who sent me some tubers) and they are nearly 5 ft tall and very lush. Really looking forward to the flowers but can't see any yet, just lots of lovely leaves. When will they flower?
Also do I pinch out the flowers after they have faded to make way for more?

Ta CF x

[cardinalflower]

[Robert_Brenchley]

Early autumn. Pinching out the flowers isn't really practical as they're well out of reach.