You can use this parameters and options for orders modified in last 30 days

                OrderSearchParameters parameters = new OrderSearchParameters
                {
                    SqlMetaWhereClause = $"Meta.Modified <  GETDATE() - 30 ",
                };

                OrderSearchOptions options = new OrderSearchOptions {Namespace = "Mediachase.Commerce.Orders"};

Or use Meta.Created for orders created in last 30 days

Thanks for the information