Here is my take!

Open one account in either Vanguard or Fidelity.  You just need one account.  Put $900 in an ETF symbol 'VTI', the other $100, you can use it to buy the stocks you like.  As you are getting closer to your retirement, you need to reduce that $900 from buying VTI and buy bond funds, like 'BND'.  At your retirement, you asset allocation should be around 50% VTI / 50% BND.  Good luck.