Your antigen is small, therefore it may need more immunizations than with larger molecules. I would suggest a minimum of three rabbits, a minimum of 5 immunizations and a large amount of Ag. 100 to 200 ug Ag is a good start. I strongly recommend against CFA (Complete freund adjuvant. This very effective but rather painful and irritant. In my hands it has caused abscesses and discomfort to the rabbits.There are a great number of adjuvant alternatives, SEPPIC has several choices you can use, they are mild and induces a good antibody response. Other than that the calendar is pretty much as in any of the choices Pierce announces.
Thanks to both of you for your answers. I was hoping somebody have done this with smaller antigen quantities, because I have 25 ug of purified protein and I needed to know if that could give me a satisfactory response. But both of you confirm what I've read from other sources, so I'll have to get more antigen in order to proceed.