if your bindings were set up properly for your previous set of boots then 1mm shouldn't mean any need for adjustment but you can check it for yourself by clipping the boot in and the screw at the base of the heel-piece should be flush with the housing. See page 24 diagram 5.3 - 13 for how to check the forward pressure on markers (
https://d3swkta9jjxguv.cloudfront.net/user_upload/marker/Downloads/THB_Marker_17-18_englisch.pdf). If you're really not confident or it doesnt look like it should, take it to a tech.