Ease In values for post-process exposure

Greetings everyone!

I was trying to find a way to put the exposure bias down when the player enters a volume and goes normal using a simple delay.

I can make the change happening using this setup;

However, there is no soft transition. I tried messing with the Ease node but can’t get anything from it.
What would be the best way to do it? Quick and dirty is allright, it’s a one time feature in the game.

Thank you for your time!

Well, I kinda resolve the problem by using a Sequence in wich I animated the exposure values. That was the only way for the time to get the effect I wanted.