Building a scorecard
What you describe it is NOT a typical approach for scorecard design.

Typically binary target - "0/1" is used for target variable and logistic regression is typical method to create a scorecard.

Typically to define "default trigger" one fixes two time periods:

1) fix say 1 year from credit start, that means defaults happening after 1 year are not considered as defaults

2) fix say 90 day period - means "default trigger" is 1 if client delays payment for more than 90 days from the payment date, that means you do not consider as "default" if delay is less than 90 days. 

There can be some other conditions - like threshold on amount of delinquency - if below - do not consider as "default". And may be some other.

You might consider the book:

Credit Risk Scorecards: Developing and Implementing Intelligent Credit Scoring 

by Naeem Siddiqi