You can use  Widget parameter Advanced > Scale ( D || W || M ) - it configures the scale of the timeline. The allowed values are:

  • 'D' - day
  • 'W' - week
  • 'M' - Month



Expert Trick: 

You can override the setting by the  Advanced > Gantt Configuration Script


    gantt.config.scale_unit = "month";
    gantt.config.step = 1;
    gantt.config.date_scale = "%F, %Y";
    gantt.config.min_column_width = 50;

    gantt.config.scale_height = 90;

    var weekScaleTemplate = function (date) {
        var dateToStr = gantt.date.date_to_str("%d %M");
        var endDate = gantt.date.add(gantt.date.add(date, 1, "week"), -1, "day");
        return dateToStr(date) + " - " + dateToStr(endDate);
        };

    var daysStyle = function(date){
        var dateToStr = gantt.date.date_to_str("%D");
        if (dateToStr(date) == "Sun"||dateToStr(date) == "Sat")  return "weekend";
        return "";
        };

    gantt.config.subscales = [
        {unit: "week", step: 1, template: weekScaleTemplate},
        {unit:"day", step:1, date:"%D", css:daysStyle }
        ];