This is a demo tutorial. While there is no step-by-step commentary available (yet), the live demo below is fully functional. Feel free to open it for full source code.
This demo shows how we can use bullet "states" to display them only when their respective category or date is hovered with a chart cursor.
See the Pen amCharts 4: Show series bullets on category/date hover by amCharts team (@amcharts) on CodePen.24419