check box for "all dates the same" and then need to fill in one date and auto fill other four

Is it possible to have a checkbox to indicate that all the dates are the same and then fill in the first date and have the next 3 date cells be filled.  I can do this if you click on checkbox after entering the first date.  But I need to change it so you don't have to click again after entering the first date.  Any ideas?

Thanks.

Christina