Create a column to copy date(s) from the table heading(s) into each row of the spreadsheet

I have a standard spreadsheet output which includes a date in the heading for a group of data in one row. This is then followed by followed by several rows of associated data and then another table heading appears with a new date.

In order to do more analysis I would like to label each row of the spreadsheet with the appropriate date, which I currently do manually. Column G in the attached spreadsheet is what I have done manually, and if possible I would like to be able to reproduce in a more automated fashion given the spreadsheet tables get quite long. Where is gets tricky is that tables are not all the size and the dates are not necessarily in time order. Any help would be appreciated?

Thanks