Monarch Caterpillar - Day 12

Two days ago I decided to replace the wilting piece of milkweed with a fresh piece. The caterpillar had been eating consistently all that day. After he crawled onto the new piece of milkweed, he didn't move or eat for over 12 hours. I got a little worried that I had done something wrong so I emailed my Monarch expert friend, Jamie. She told me not to worry - that it is normal for the caterpillars to have periods of dormancy afterwhich they will shed their skin. Sure enough, I was keeping a close eye on the caterpillar yesterday, went outside for about 45 minutes and when I came back I found this:

I had to run a quick errand and when I came back, the caterpillar had eaten the skin it had shed and its antennae were still not fully extended: It didn't take long for the catepillar to start munching away on the fresh milkweed. And today he is almost doubled in size!!

It drives me crazy that I continue to miss the different phases of the caterpillar's development. I wish I could set a camera on the entire process. It really would have been neat to watch the caterpillar shed its skin and it happened in such a short period of time! Always when I am not looking! It's still days away - but I really hope I don't miss the caterpillar turning into a chrysalis. I missed it last year - again it happened in about one hour when we weren't looking - and I was really disppointed. I have seen it once on film and it was truly incredible!

Jamie, if you read this will you tell me how long I can expect before the caterpillar will make a "J"?