As a rule, waiting until all the leaves have turned brown is too late. The "papers" that hold all the cloves together will have broken down and all you will have is loose cloves.

Unfortunately, your late planting will probably not yield much. But there's always next year...

My understanding is to wait until about 50% of the leaves have browned - only 1 or 2 per plant are brown at this point. Is that incorrect?

I usually yank em when top growth leans over. Most of the time they still have plenty of green left.

Sounds fine to me. I try to dig when there are at least 3 nice leaves left on the plant.