How to be tactful when pursuing a lead after a death

[Nicole Heasley Beitenman]

Hi BP!

We know of a family planning to sell a home after the death of a family member, and we are interested in buying that home. We know the family well. While we don't want to be insensitive, we also don't want to wait too long and find out that the family has already involved a realtor. So that leads me to my 2 questions:

1) What is an appropriate time to wait before approaching a family about their recently deceased loved one's home? 

2) How do you tactfully ask someone about buying said home without coming off as a vulture?