It doesn't work with multiple start dates.
Can you explain why it does not work or what you are having difficulty with in implementing the tutorials mentioned? As illustrated in Jeff's links (and explicitly stated in the Excel help file for Gantt charts https://support.office.com/en-us/art...7-F0FB34D9E2B6 ), A Gantt chart in Excel is simply a stacked bar chart with appropriate formatting.

Looking at the simple table that you have, you would need to calculate a couple of "durations" (manufacture date-design date and retail date-manufacture date), then use those columns in addition to the design date column in a stacked bar chart to get a simple Gantt chart. Are you thinking of something different?