I don't pinch mine as I would mums. I usually trim them pretty hard before they start to green up for spring. I would suggest that you cut off any dead looking stuff now, but leave what's green. The flowers usually form at the end of each branch; not sure at what point they start to form but if you cut now, you might lose those blooms. I'm not an expert on Montauks but have been growing them for about 10 years and am just relaying what I do.

You have me beat by nine years. I will go with your instructions. I love them and want them to blossom nicely.
Thanks.