I want to add that when you first open this, there are air gaps in the tube, so the plunger has a lot of wiggle room. Keep the cap on and push the plunger to tightly compact all the paste into the exit end. Tap the tube multiple times on a hard surface to force the paste to settle in more. Repeat.
Even after getting it all compressed into the end, there will be about an inch of unmarked plunger before the weight notches start. How does one handle that? It will be adding substantially to the first dose.
A new tube of horse paste is unevenly filled at the tip of the syringe. You can push the plunger until the "sloppy" part of the gel is out of the syringe and the gel appears to be evenly filled. Around this point, the unmarked portion of the plunger should be inside the tube, and the plunger should be around the zero mark.
The extra bit of unevenly filled paste can be discarded. Or you can eyeball it to estimate how much extra paste there is by comparing it to a standard dose. Then you can take the extra amount if it is merely giving you a double dose.
It is normal for people with active COVID to take a double or triple dose. The standard dose is the preventive dose for people who have not yet caught COVID.
This is a mild and safe product, so a lot of people would probably rather take a little extra instead of throwing away the excess from the starting end of the syringe.