This all depends on the variety. If it is still green it is growing somewhat.
Some time after it stops growing the shoulders will start to turn dark.
Soon after that it will quickly furn red. (if it doesn't turn some other color.)
I pick very fresh peppers at the store that look like they are getting very dark (almost black), many times they turn red on the shelf.
Sounds like a politicians answer.
You could try circumnavigating the garden in the nude, this sometimes makes them turn red.
Again this depends on the variety.
Worth