Function to discount shipping charge if ordered before 12 noon.

I have a woocommerce site for a flowershop that delivers orders that are made online. I wanted to offer a delivery charge discount if the order is placed before 12pm.
So I believe I need to use this hook
http://hookr.io/actions/woocommerce_cart_calculate_fees/
and I need a function that will get the current time and if before 12noon add like a 25% discount to delivery charges.

Can you help with that or is that beyond the scope of support?
Thx!