The third week of September and the show is just beginning.
Update, to answer some comments:
My plants came from GRDN in Boerum Hill, Brooklyn in early summer - and I asked Suzanne to order them as she did not know them. She ordered from her wholesale grower. I would call your local nurseries and ask them about availability and request it. This plectranthus (developed at Kirstenbosch in South Africa!) is becoming quite well known, so I think it might not be too hard to find, for them. If they don't know it, tell them it will bloom until frost.
I planted it in...I'm guessing, June? It had some little, forced, flowers then, and was a manageable size, 6". The first flowers disappeared while they grew big and leafy. The plants are now almost two feet tall and wide. But I have used them as seasonal annuals in fall before, so perhaps nurseries still have them - they certainly will look good to customers right now.