Before blue does nothing. The blue is actually a liquid the snakes body makes to help with the shed. Once the snakes body absorbs the liquid is when they will begin to actually shed. That is the time they need the extra humidity to keep the old skin from sticking to the new skin.
But in all honestly, you should keep the snake's humidity correct all the time. Too low of humidity over the years can actually affect the snakes internal organs and liver or at least I was told that. I keep my boas, BP and retic at around 80% with the cocochips. Stuff is awesome and the snakes seem to love it except my JCP. She seems kind of scared of it and wont actually sit on the floor lol. She goes from her perches to her rock hide and then back up on the perches. It's like when you were a kid and jumping on the furniture pretending the floor was hot lava![]()