There is no really good way to do this. Anyway you do it is a bit of a hack. The way I have done it is to create a sql agent job that checks for the existence of data for the report then us sp_start_job to fire off the job created by SSRS for the subscription if data exists. Like I said it's a hack, but it works.
Jack Corbett
Consultant - Straight Path Solutions
Check out these links on how to get faster and more accurate answers:
Forum Etiquette: How to post data/code on a forum to get the best help
Need an Answer? Actually, No ... You Need a Question