The startDate property sets the visible range start. In addition to DayPilot.Date object, it also accepts a string in ISO 8601 format ("2021-01-01T00:00:00").
If not specified, the start date of the first (earliest) task will be used.
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Using DayPilot.Date object:
dp.startDate = DayPilot.Date.today().addDays(5);
Using ISO 8601 date string:
dp.startDate = "2022-01-01";