I could stop biting my nails using some TAPs.
Installing the TAPs took at most a few days, and I think I might have failed and bit the nails some times.
It took around a month to get the nails long enough that I could cut and polish them, and after a while the TAPs disappeared completely because I didn't need them anymore.
According to my journal, I started using the TAPs on 20180612 and cut my nails on 20180714, and there is also a register on 20180703 that I was not using the TAPs because their trigger had disappeared.
I think that what made me bite my nails was that they had a dent or something like that that I could play with, and after I did some damage to it using other nails, I eventually bit it to remove that part that stood too much (I still do something similar with the skin around my nails, and I've never thought about getting rid of it).
After I could cut them for the first time, I only bit them once when one of them get broken.
I don't remember exactly how I felt at the time (I haven't write about how I felt in my journal), but I think it was like an accident that happened and I just had to keep doing what I was doing and everything would be fine.
I remember that I had bitten my nails since I was around 10 or even younger (I'm 30 now), and I couldn't stop definitively until I used the TAPs, sometimes the nails would grow, but eventually they regressed to the bitten state.
I used two TAPs:
Biting nails #1
Trigger: Looking at my nails
Action: Close my hand
Biting Nails #2
Trigger: Rubbing my fingers with the thumb
Action: Open hand
It is a complementary trigger to avoid damaging the nails without even looking.
I didn't have a TAP for biting the nails (having my finger in the mouth) because I never noticed doing it without looking at them first.
It has been one and a half year since I stopped, and I think I might have bitten the nails some times, but it was not enough to keep biting them similarly to the case described above.