Paul Sturrock's side lie 7th in the League Two table ahead of their weekend clash with Northampton and have re-signed Timlin for a second loan spell at the club.
"I'm delighted, it's taken a while, I was waiting around for it for about a week," the midfielder told BBC Essex.
"I told the chairman from the start I was eager to come back here because I enjoyed my time here last year."
Northampton meanwhile have extended the Sixfields' stays of Ashley Westwood and Peterborough loanee Kelvin Langmead until the end of the year but have allowed Kevin Thornton to leave the club.
"He had to have an operation and never really got back to the level he had in pre-season," assistant boss David Lee told BBC Radio Northampton.
"He came back and did well in pre-season, his fitness was good but you know with budgets at clubs nowadays and the players we have got in that position, I think the gaffer felt he'd be best playing somewhere else."