client is sending milliseconds for start time
diff --git a/superset/sql_lab.py b/superset/sql_lab.py
index ea91133..07063c7 100644
--- a/superset/sql_lab.py
+++ b/superset/sql_lab.py
@@ -233,7 +233,7 @@
         )
     if apply_ctas:
         if not query.tmp_table_name:
-            start_dttm = datetime.fromtimestamp(query.start_time)
+            start_dttm = datetime.fromtimestamp(query.start_time / 1000)
             query.tmp_table_name = "tmp_{}_table_{}".format(
                 query.user_id, start_dttm.strftime("%Y_%m_%d_%H_%M_%S")
             )