When we installed new carpeting years ago, I made new base boards and installed them with brown, almost invisible flat head screws.

Getting new carpeting soon. Should I leave the baseboards in place or remove them and reinstall them after the carpet is laid? Or should I leave that up to the carpet installer?

Carpet goes up to the baseboards. If you were having hard flooring it makes for a neater and easier job to pull up the baseboards and than re-install on top. Only reason to pull them up for carpet would be to paint or stain them but I would still put them down before the carpet comes.

The installers will stretch it over the tackboard edging then tool it under the baseboard, so it doesn't seem like you should have to pull it just for an install.

Leave them. The carpet will tuck up to or under them. Baseboard should be installed with a gap between it and the floor. Some people, however, improperly install it all the way to the floor. Either way, the carpet will work.

That's what quarter round and shoe mold are for. Leave the baseboards.

Leave the baseboards, but remove the more or less quarter round "shoe" or "toe" molding (if you have it) at the bottom of the baseboard. The carpet installer will place tack strips close to the baseboard, then kick stretch the carpet right up to the baseboard over the tack strips.
If your baseboards need any touchup refinishing (paint, varnish or stain) work, whether from usage or from removing the toe molding, it will be much easier to do it after the toe molding is removed, but before the carpet arrives.

In my part of the world, we don't use quarter round or shoe mold on carpet-just wood, tile, linoleum, etc. so that shouldn't be an issue when going from carpet to carpet.

Ameridaddy does have a point about repainting. It will be much easier to do any baseboard painting that you may want to do with the carpet removed. This, of course, means you would have to remove the carpet and do the painting before the installers arrive. They'll scuff it up some with their stretcher, but that would be easily touched up. You'll want to give the paint several days to cure before the installers are scheduled.

Hopefully when you installed the baseboard years ago it was prior to the carpet. If so the old carpet gets removed, the existing tack strip can usually remain, and the new carpet works right back up to the base.

If you installed the base after the carpet was installed, therefore on it, it's going to be more difficult to remove the old carpet. Especially if the base is on the tack strip.

If that's the case you should remove the base, then cut and remove the carpet a few inches from the walls as well as the tack strip. Then install the base down to within 1/4" or so of the floor. The carpet will then work up to the repositioned base and from then on won't need removed.