As I mentioned, my colorblindness does not allow me to see the "red" you guys speak of as tissue is about to form callus.
I don't usually see the red coloration. It's usually a change in texture or swelling of the tissue that allows me to know when the culture is going to "take". For Dionaea, it usually comes down to two things:
1) The explant sits there and does nothing and eventually turns black.
2) The explan stays green, begins to swell and starts making tiny plantlets. This occurs about 6 to 8 weeks after initialization if the explant is part of a leaf. It can take longer (much longer sometimes) with flower stalks.
Leave the meat for our pet plants