I've parsed this info from different sources and likely confused aspects during the endeavor. Hopefully someone will chime in to correct my mistakes and edify us all
First, she'll sport her "Mopar, I need a hemi' receptive colors which seem to be blue/turquoise and yellow/gold patterns and may display these 3-4 weeks. Then she may change into her grumpy gravid dress which, from the pics I've seen, is very dark/black though this may only be in the presence of a male to tell him, "back off, buddy ... you're too late." Of course, local conditions could lengthen, and possibly, shorten the process.
Chamille, once I realized she wasn't 'Cham', got her bin straight away, an ~ 7.5 gallon pot. I hadn't found enough about the process to have any sort of timetable, but 'too early' doesn't really exist and gives her a chance to accept it as part of the scenery by the time the digging starts. She first showed her receptive colors at the beginning of November and would follow me about from the inside of her cage. I started opening the cage and placing my hand in front of her and she'd march up my arm to my shoulders. One mid-December day, I go into her room to check on her and she's perched on the far side of her laying bin and upon spying me, steps down into the bin, marches across to the near side, and promptly starts digging in front of me and not in either of the holes I had started for her. Oooookay, guess I'll just back out and leave you to it. She spent the night in the hole she finally dug on the far side of the bin and continued to scratch around once she'd filled up her hole. I'm guessing she did this to not leave an obvious, telltale patch of disturbed earth.