FORMULAS IN EXCEL

I would like to know how to insert a formula that will tell me the delay in an activity.For e.g,a particular column has a “scheduled delivery date” and another column has “delay”. I need excel to automatically enter the “delay ” column taking the refernce from “scheduled delivery date” column.

Is there some formula that will cross check the date entered in the “scheduled Date” column and the system time and thereafter calculate the “delay” column ?