updated per this slack conversation:

[predtimechart] add a new optional initial_xaxis_range predtimechart option: {..., 'initial_xaxis_range': ["2022-04-20", "2023-05-31"]} # [2023-04-19 - 52 weeks, 2023-04-19 + 6 weeks]
[zoltar server] add a new x_axis_range_offset viz config option (recall: https://zoltardata.com/project/44/viz_options_edit ): {..., 'x_axis_range_offset': [52, 6]} _# [weeks_before_final_reference_date, weeks_after_final_referencedate]
[zoltar server] use that option to calculate the initial_xaxis_range that's passed to predtimechart
[zoltar docs] update screen shot on this page

original from @elray1 :

e.g. this could be specified as an options argument along the lines of

options = {
    ...
    "initial_x_range": ['yyyy-mm-dd', 'yyyy-mm-dd'],
    ....
};