Looking at 70 days of data the optimal working point can be more or less identified looking at the Optical gain variation for the cavities and for the Range.

The data set is visible in Figure 1.

The Optical gains shows some steps that are been compensated, see Figure 2. The red curve is the one used for the analysis

in Figure 3 the BNS range is plotted as a function of the Input mirror temperature and the maximum is obtained for 19.58 deg for the NI and 19.61 for WI.

In Figure 4 the OG for the cavities is  plotted as a function of the Input mirror temperature and the maximum is obtained for more or less the same temperatures found for the Range.

To be re-measured with a controlled experiment.