u/Beautifile

I'm just starting my business and everything I read says wait until you get your final LLC papers and your EIN to apply for a business bank account and credit card. First of all, is this good advice as I have a very good credit score and for now the business is just me? Also, Can I still count something as a business expense if I pay for it out of my personal account then later pay myself back? Right now I'm mainly concerned with the Articles of Organization fees and the fees to advertise in the newspapers here in NYC.