Best time to cut Hydrangea blooms for drying

I've managed to get my indoor hydrangea to bloom outside in a pot. It's beautiful and blue without the help of aluminum sulfide. Of course I want to keep the blooms and dry them. When should I cut them off the stem? They're in full bloom now and have been for about 2 weeks. When it comes to the drying part, what is the best procedure? Ugh, thanks for your advice.
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