The Trotters boss is keen to see a quick resolution to the saga surrounding the 25-year-old defender that disrupted his preparations for this season
The Scot does not want to see a repeat of August's deadline day which saw Tottenham and Arsenal make late moves for the centre-back and the saga disrupted his preparation for the new season.
With Chelsea now believed to be in the driving seat to sign the 25-year-old Coyle is ready to cash in during the January window, with the defender's current deal set to expire in the summer.
“If something comes in, it would probably be better sooner rather than later," he said, according to the Daily Mirror.
“The further we get into the window it can make it a very difficult market.
"It’s fraught with danger, we can all accept that.”
The Bolton boss has endured a tough start to the Premier League season and finds his team occupying a relegation place after 12 games.
It is likely that any money generated by the sale of Cahill would be available to spend in January but Coyle appeared calm over the situation.
He added: “I’ve not had any money wherever I have been. I have been inventive. There are ways and means of going about it.
“If we do have the luxury of money, great. But I won’t beat myself about it if I don’t. I’m at a fantastic club with great people in every department.”
The Bolton manager was less relaxed when talking about the injury-jinx that has plagued his squad this season as he battles to avoid the drop.
“In all my time in football I have never known things as severe as this," he said.
“The long-term injuries are incredible, the top players and some young ones as well. It has been a catalogue of injuries.
“We don’t have a big squad, if some clubs get injuries then bring in players of the same level. But we still have a group that can win games.”