I have a Google Spreadsheets that is used by different people to add tasks for my team. Here's an example. People can add tasks to column B and I will assign them to the right people in the team, filling in the other columns. The first field I'm capturing is the date that a new task is logged. I'd like to automate this so that when people add a new task starting in column B, column A gets updated with the date that the new line is created.
I've found scripts that will update the timestamp in column A based on changed in column B, but I only want to log the creation date. In other words, when there is already an entry in column B and it gets updated, the date in column A should not change. Only when column B changes from an empty cell to a new value should column A on that row be updated with the date.
In the above example, if I change the task on line 2, the date in column A should not change. If I add a new task in cell B3, it should add the current date in cell A3.