Information on Duration or Start/End Time

My question has split my team in the middle, so I'm here for more opinions. We have this Gantt Chart where you can extend/shrink tasks by hovering then dragging them from start/end. When this interaction starts, a tooltip appears with the information on the active edit.

Such as:

So our main issue is with the interaction from the start of the task. Should the tooltip show Duration as in the example, or should it show the relative Start Time? (That would mean the last to tooltips would be - 20 min / + 20 min)

Thank you in advance :)

Note: I'm trying to make it as small as possible, this is just one feature of the chart, the overall is a very crowded UI.