Most banks will require that you be a legal resident for a short period of time before opening a local account so most expats do get their residency visa first, operating via home credit/debit cards in the interim until they can get a local account set up. Having a local account makes many things (like paying for local utility bills) easier. Though there are some expats who don't open a local account, it's recommendable to do so.
Best,
IL Panama Editor Jess Ramesch