CA is great for P. Take P before SRM in order to make sure you have enough conceptual understanding of all the distributions, and the only parts of P that are extended to SRM are the different distributions and their concepts. You don’t need that much time to prepare for either as they are both not the most difficult exams, I prepared for both a month each. I used CA for both but CA wasn’t as good for SRM. Although, I don’t know if anything is good for SRM since it’s still ‘new’ in that there are only 60 practice questions. I remember that my actual test’s questions were structured very differently from CA and the SOA practice questions but P and SRM should both be doable no matter what.