diff --git a/src/Concerns/ManagesUsageBilling.php b/src/Concerns/ManagesUsageBilling.php
index 5e4daf13..e11cf2af 100644
--- a/src/Concerns/ManagesUsageBilling.php
+++ b/src/Concerns/ManagesUsageBilling.php
@@ -59,7 +59,7 @@ public function meterEventSummaries(string $meterId, array $options = [], array
     {
         $this->assertCustomerExists();
 
-        $startTime = $options['start_time'] ?? 1;
+        $startTime = $options['start_time'] ?? $this->created_at->timestamp;
 
         $endTime = $options['end_time'] ?? time();