What time dating system does Mortal Engines universe use ?

The time frame in which Mortal Engines covers is known as the Traction Era.

Time was measured in years since the first traction cities got rolling.

So time is measured in Traction Era (TE) years.

To my reading, this is not exactly explicitly referenced in the Mortal Engines series itself.  

For some context, municipal darwinism began at the same time the Traction Era began and we know that at page 9 of ME that this form of Darwinism has existed for a 1000 years.

But we must of course consider the timings around what caused the Traction Era to begin.

Mortal Engines is set in a post-apocalyptic world, ravaged by the so called "Sixty Minute War", which caused massive geological upheaval and the destruction of humanity. The war resulted in the subsequent struggle of restoring civilization and technology and reclaiming that element of lost humanity.

We know that the whale that hangs in Tom's Museum on London City was extinct for thousands of years. We only assume this happened before the Sixty Minute War began.

Phillip Reeve’s ‘The Traction Codex’ gives us some insight into the time line.

“After the Ancients destroyed themselves in the Sixty Minute War, there were several thousand years in which nothing much happened. These were the Black Centuries. The great civilizations of the Screen Age had been utterly swept away, and humanity was reduced to a few scattered bands of savages’