generally, APS is added to an aniline solution (in acid), and you should take care of controlling the temperature very well (keep it around 5 degrees, and don't let it jump up and down).

This is in other words the reason why you would not add aniline into an APS solution: you would start with an extreme surplus of APS and over-oxidize the resulting polyaniline into the pernigraniline form.

Thank you sir, for your answer. As we know that emeraldine form is only conducting in nature and by doing this way we also got conducting PANI. So, is it true that only molar ratio of oxidant to monomer ratio much matter rather than the addition of monomer in oxidant or vice versa.  

for getting best, optimal PAni (highest conductivity, optimal dispersibility) you need to control the temperature as I explained above

thank you sir for your reply.