job title

Hi Xiaobaitu,I have a question and need your help.I have 1 year experience in the first company with web programmer job title,then I have more than 5 years working experience in the second company(current company) with application programmer job title. Now I want to apply PERM using EB2 bachelo's degree+5 years(total related years, not only web) working experience with web programmer title. My question is when I should start to change my job title? now or later when PERM get approved? Which way is more reasonable by law? What is the best way? Thank you very much!