Print to the left (or right) of an A4 landscape

I print labels from the courier to stick on the parcels I send, but the PDF I receive only allows me to print in the centre of the page.

My labels are 2 x ½ page (A5) labels on an A4 page, which effectively makes them A5 labels.

When I try & print the labels, I had hoped to choose A4 landscape so that I could print it on one of the labels, however, it will only print central to the page, meaning it prints ½ on one label & ½ on the other label!

How can I force a PDF to print the alignment of the page left (or right)?

Thank you in advance