Borderless printing sounds like a great idea in theory - and certainly visually it can look nice to create a completely edge to edge print.
But doing a lot of borderless printing, overall, is not a great long term plan - it can shorten the life of your printer and lead/contribute to lots of issues like head strikes and ink blobs on your prints.
Borderless printing works by basically enlarging the image over and beyond the physical edge of the page - that is, your image will always print a little larger than you want it to, and a small amount of the image at the edge will get cut off.
There are some driver controls you can use to minimise this expansion, but by definition to be sure it covers the edge, it has to go off the edge. And this means, physically, your printer must spray ink PAST the edge of the page. There are pads for this overflow ink (in certain positions - this is why you can only print borderless in some sizes) - but these pads are not infinitely able to soak up ink. Before long this ink over-spray can cause a variety of issues, so minimising the amount of borderless printing you do is a really good idea.
Also, borderless prints are MUCH harder to physically handle, as one basically must then handle the actual printed image edge (which shouldn't be handled - pigment inks are not really meant to be touched on the inked area as such). And if you want to frame the prints, the framer will have to overlap the image with the matte as there's no spare paper. Framers much prefer to work with prints that have a little bit of blank paper around the edge.
So more than anything else, our advice is to suggest you very strongly consider a general practise of leaving a border around your prints (2cm or so is a good minimum for that).
Most people ultimately come to the conclusion that prints with a border simply look better - more like an art product, less like a poster, and it allows the viewer's eye a bit of relief from the image - and gives the viewer a real sense of the quality and physicality of the paper too. And for the reasons above it works much better, practically too. If you look around you'll see that almost everyone selling art prints regularly does leave a border.
If you really don't want a border, then the best long term approach is actually to print as a bordered print on bigger sheets - say A3+ - and then trim from those a borderless A3 image AFTER printing, using a proper trimmer.
This will prevent ink build up in your printer, and also stop the image expanding issue, so you'll be able to get pretty much just the size you want (note though inkjet printers are not 100% mm perfect in anything, so you may still experience a mm or two of difference between your layout size and actual print size).