diff --git a/lerobot/configs/policy/act_koch_real.yaml b/lerobot/configs/policy/act_koch_real.yaml
index fd4bf3b59..e72a6a3fe 100644
--- a/lerobot/configs/policy/act_koch_real.yaml
+++ b/lerobot/configs/policy/act_koch_real.yaml
@@ -42,7 +42,7 @@ training:
   online_steps_between_rollouts: 1
 
   delta_timestamps:
-    action: "[i / ${fps} for i in range(${policy.chunk_size})]"
+    action: "[i / ${fps} for i in range(1, ${policy.chunk_size}+1)]"
 
 eval:
   n_episodes: 50