I'd keep the extra couple of links and tie them back as others have mentioned. That is what I do.
Why?
1) tire diameter for a given size does vary even within a tire brand. Your next set of tires of the same "size" may actually be a different diameter, larger or smaller. Not a lot, but enough to make you wish you had the extra link or 2
2) and unless the tires are brand new, you may need the extra links again anyway.
3) while installing them in the driveway in nice weather is easy peasy, doing the same in a chain up area is not as easy peasy. you may end up using all the links then drive a few hundred yards, get out and tighten, drive again and repeat to get them as tight as you want. And you'll like the extra links.
