Fields that auto calculate date based on user input date.

I have a form that requires 7 day history from date of application. The user inputs the application date. I then have 7 separate fields that should auto calculate the past 7 days from the user input. For example: user input = 06/07/2018

With the dates in the table above being auto-calculated in 7 separate fields. Let me know if I'm not making any sense. Also, here's something that I found to try and adapt to what I need, but my coding knowledge is small and not in Java at all haha so any help is appreciated.

var dateString = this.getField("Date of Application").value;  
if (dateString=="") event.value = "";  
else {  
    var d = util.scand("mm/dd/yyyy", dateString);  
    d.setDate(d.getDate()-7);  
    event.value = util.printd("mm/dd/yyyy", d);  
}  

Thanks.