What possible effect could opening a bank account have on your credit score? You're not borrowing money.
I say again, people worry FAR too much about their credit score. Live your lives the way you want, it will be fine. Just avoid the obvious stupid maneuvers like applying for 10 credit cards in a short time, paying late, etc.
My score has varied from 760 to 798 over the past two years and I haven't done anything different. Income, loans, credit cards - no change. If I spent a lot of time trying to figure out ways to influence it, I would have wasted all that time. The scoring system is secret for a reason - so people can't purposely manipulate it.