Thanks for this suggestion, Amber. Fortunately, this was a simple tweak on our side, so we’ve enabled the opening hours (AKA delivery window) section on leads now 
Please allow up to a few hours from now for this to appear on your account.
I see you’ve also voted for Customer and lead mapping and visit (field sales) route optimisation too, so these opening hours will be able to be used when we add that functionality. Cheers 