To get the magnetism in the nonmagnetic host material, I would like to know how much percentage doping we can do. Is there any minimum or maximum doping percentage defined or it is different for different materials?
It really depends on the solubility limit of dopant in host material. Start with the lowest level of doping you can. less than 5 % of dopant concentration should be ok.
You can follow this article as an example.
Article Stabilizing intrinsic defects in SnO$_{2}$