diff --git a/Config.go b/Config.go
index a36901b..971ca51 100644
--- a/Config.go
+++ b/Config.go
@@ -26,6 +26,11 @@ type LogSource struct {
 	FileLocation []LogLocation
 }
 
+func (this *LogSource) EarliestDate() YearMonth {
+	// assume it's the first in the list (although it might not be)
+	return this.FileLocation[0].StartMonth
+}
+
 func (this *LogSource) LatestDate() YearMonth {
 	// assume it's the last in the list (although it might not be)
 	end := this.FileLocation[len(this.FileLocation)-1].EndMonth