Hi Bishir. Welcome.
Every lab does it a little differently I’ve found, which is one reason for the wide variability seen in the literature.
The most detailed protocol I’ve seen is from Jax, which I think is as good a source as any to imitate since they’re a major mouse breeding and phenotyping site
You may also consider SUDO from @Boninrp, which is a simpler version of the von Frey assay that has found an audience in recent years. When I use conventional filaments, this is what I do
We discussed it previously
Good luck!