The location I get my perch from is 2,000' above me in elevation and I think I have a way to make this work.
His perch don't start blowing ribbons until about 2 weeks after our artificial hatch of WAE/SAE.
I know last spring he had ribbons showing up when I started seeing a couple of SMB on beds at my place, so up to 5 weeks after..
I'm at the southern end of the egg take so I have the earliest window and one that could be easily missed.
If nothing else, it provokes thought.