What you want is to add one of the Cement Perches to his cage full-time, not just for a week, but all the time. The Cement Perches are totally safe, they are not the same diameter throughout but rather all different diameters like a natural tree-branch is, and if you place one inside of your bird's cage full-time from now forward, it will not only keep their toenails filed and you'll no longer need to clip their toenails much at all (except to occasionally take the very point on the ends off), but they also use the Cement Perches to file the tip of their Beaks on as well, keeping them rounded and preventing any "needle-beak" from developing...
***But again, you must keep the Cement Perch inside of their cage full-time from now on, and put it in place of one of his regular perches, preferably the perch that he spends the most time on, so that he'll be using the Cement Perch on a regular, daily basis from now on. That's the only way to keep his toenails trimmed and from over-growing in total-length; if you only put the Cement Perch in his cage for a week or so it will simply result in the tips of his toenails being rounded-off and not pointy, but you'll still have to clip all of his toenails regularly because their overall-length will continue to grow. In contrast, if you remove whatever perch he spends most of his time on now with a Cement Perch and leave it that way, then the overall-length of his toenails as well as his beak will be kept in-check, and he'll rarely require any nail-clipping.
The "sandpaper" perches that you were talking about (also those sandpaper perch covers that you slide over regular dowel perches) are not good for a number of reasons. The main reason the sandpaper perches are bad is that they are just dowel-rod perches with a rough, sandpaper outer surface, and they're all one diameter throughout their entire length, and this will result in Bumblefoot. Also, the sandpaper can actually hurt the skin on their feet, and they also tend to fall apart and break often...
In contrast, the Cement Perches are shaped like a natural tree-branch and are different diameters throughout their length, they prevent Bumblefoot, and they are heavy-duty and will not hurt their feet at all and are completely safe. I have had one in each of my 4 larger bird's cages since I brought them home as little babies, as well as having 2 of them in my Budgie's indoor-Aviary, and rarely do I have to file even the tips off of their toenails or their beaks. Totally safe, effective, and absolutely the best way to go.