It usually takes longer for older corns. But It would probably take about one week.
Here are the stages of the shed cycle:
First the snake's colors get really dull and then their colors get opaque (Most noticable on Amels) But you can also tell with the eyes and how they get cloudy. After that, the snake will clear up and it will look like it has already shed, but it hasnt. After the snake clears up, it will take about 2 or 3 days for it to actually shed. Many people get scared when they see the snake clear up but they dont see the snakes shed.
And snakes will ususally hide when in shed, they like to be left alone durring this process.