There's current discussion about what the value of TDCWhileCranking should be.

TDCWhileCranking controls the advance of the spark when the engine speed is less than that for the first column - usually 500RPM. Normally the advance is taken from the map but if TDCWhileCranking is set to 1, the advance will be zero.

The reason this was added was because a number of bikes were kicking back, causing lots of stress in the starter, and of course failing to start. TDCWhileCranking was added for these bikes and because it seemed to work better on my bike also, became the default.

Normally I would not expect much variation in the starting behaviour as the first firing should increase the RPM above the first column RPM and hence TDCWhileCranking would not matter. However a number of users are having difficulty starting when TDCWhileCranking is set to 1.

Having thought about why the big difference, the only explanation is how the engine signal triggers the ECU when starting. The signal is a weak sine wave of greatly varying amplitude and frequency. The ECU is actually tracking the waveform in real time. The current logic determines that the trigger point is when the signal is equal to the mean voltage plus 1/4 of the amplitude.
With a perfect sine input this occurs at 30 degrees which for our bikes is actually 15/12 degrees. So TDCWhileCranking=1 actually 1 degree after TDC.
Add in real world variations like the actual signal level from the sensor and the engine speed variations, this may explain why some bikes don't work well when this value is set.

In anticipation of the question, when the bike is running the engine signal expands into a square wave so the above variation in timing doesn't occur.

The bottom line is use whichever works best for your bike.

Regardless of the TDC value, I`ve seen other ignitions having a parameter called Revolutions w/o firing when starting. The engine gets a rev or two to get rolling before ignition starts.
Is that avaliable in MyECU?

No that's not available.
What are you trying to achieve with that?

Easier to start if engine has some inertia before ignition starts, less risk f kickbacks f e.