Testing staged dunning

Hi ,

We have developed custom dunning letter templates and attached then to the dunning plan.

The dunning method we are using is staged dunning.

Can someone please let me know whats the best way to test the templated in staged dunning.Especially the dunning levels are drived by the number of days,

There are three templates and the dunning levels are;

1-1 - Letter template 1 ( after one day )

2-2 - Letter template 2( Afte  7 Days )

3-99 - Letter template 3 ( after 14 days )

Thanks and Regards,