It is not important where we actually start laying track. The first splinepoint (fig.07) of the first track is placed right around the stem of the pinetree with the stem right to the center of the circle. (That is why I take a pinetree with a long stem).
fig.07
The free splinepoint to be put around the stem of the next pine ...(fig.08)... and so on for all the trees you have placed before. If you have a double or more tracked line you may appreciate now the pinetree to remind you where you started putting tue rulers ...
fig.08
Finally you will have a picture like the one in fig.09.
fig.09
If you realise, that the track you started from does bend, thet you have to straighten it with the tool from the surveyor menue, same as with the straight track on the distant end.
Please note, straightening the endtracks is essential, otherwise Trainz will put down something pretty undefined.
You could check the shape of the curve (fig.10) in the miniature map of surveyor's starting menue, but I sometimes get the impression that we have some distortion there.