There is a need to know the size of the document before printing
The roll paper printing is printing just specified lengths. It is not printing until everything is printed.
You need create different lengths of paper like 1m, 1.5m, 2m, 2.5m, 3m ... To select the correct length of the paper, you need to know the size on the document.
The current workaround to find out this, is to print pdf to different lengths of paper and look which seems to be the right length.
The document info before printing simplifies this.