SAP MM or PP to get into APO DP & SNP

Hi experts,

I am a fresher intended to pursue a career in SAP with emphasis on APO module. I would like to know on which module i.e., MM or PP, I need to learn in order to get a head start. My primary focus would be initially on APO DP & SNP and later into PPDS and GATP.

Are any of these modules required for learning APO DP/SNP.