Adding extra_x_range and adjusting it according to the x_range of primary axis

I have added extra_x_ranges to my plot by :
p.extra_x_ranges = {“range_hist_freq”: Range1d(start=2000, end=0)}. But I want the 0 of this new x-axis to be plotted just in front of some value in old x-axis. here the old x-axis is in the datetime format. Is there a way I can do this?