Improve the warning about deletion

hiboo/models.py

@@ -127,8 +127,11 @@ class User(db.Model):
         """
         if self.profiles.count():
             return None
+        timeout = User.get_timeout()
+        if datetime.datetime.now() - self.created_at < timeout:
+            return None
         last = self.updated_at or self.created_at
-        return datetime.datetime.now() - User.get_timeout() - last
+        return datetime.datetime.now() - timeout - last
 
     @classmethod
     def get_unused(cls):