Cura Timestamp accuracy in gcode and interpretation

[3DPLAB 0]

Hello everyone

I am measuring the timestamp mentioned in cura and the actual time it takes to print an object. In my observation there is a slight difference, in some cases few seconds and in other few hundred milliseconds; this is especially true for layer-1

 

Is there any information on how accurate is the timestamp in Cura generated gcode file? 

 

I mean is it reasonable to expect accuracy of upto 10s of milliseconds? 

 

What are the variables that may cause this variation in actual time and expected time?

 

What is the start point of the time counter for layer-1? Options:

 1)The heating of printcore

2) the movement of bed to the top

3) the last movement of printhead when going towards the startpoint

4) when the extrusion starts at the start point

5) any other trigger

 

Thanks