Born in Lambeth, England, Timlin graduated through the Fulham Academy, making his debut in a League Cup game in 2004. During this time he spent time on loan at Scunthorpe United, Doncaster Rovers and Swindon Town before joining Swindon permanently in 2008. In 2010, he moved to Southend United on loan, reuniting him with former Southend manager Paul Sturrock again having previously played under him at Swindon. In January 2012, Timlin made a permanent transfer to Southend United, after his second loan spell with them had ended. He helped the club to secure promotion out of League Two in 2014–15. The midfielder signed for Stevenage in June 2018 and played an integral part during their 2018/2019 season. Timlin was out of contract the following summer and, due to personal reasons, decided not to agree to an extension. Subsequently, Timlin re-signed for the club in September 2019 on a short-term contract playing under a different manager to his previous spell. In January 2020, Timlin signed for Ebbsfleet United however due to a transfer embargo in place on the club at the time, he was unable to make his debut until mid-February. As a result of the Covid-19 pandemic, the National League season was curtailed in April with Timlin having made just 4 league appearances. In August 2020 it was announced the midfielder had joined Dulwich Hamlet in a role combining playing for the first team and coaching in the Academy.