It surprises me that the fstrim.timer is not used like in other distro's. This ensures that once a week the trim command is executed automatically so you can't forget it, and also that you don't do it too often.
A continuous trim is, according to many, not necessary and also not something you want cause it can damage the SSD.
What I normally do is:
sudo systemctl enable fstrim.timer
sudo systemctl start fstrim.timer
Plus, of course, remove the discard option in the /etc/fstab file for every partition located on an SSD.