Agreed - whatever you get, get it well in advance and know it inside and out. It’s a tool. You can’t use a tool effectively if you’re figuring out how it works as you’re trying to use it.
Getting a “good calculator “ because “I can program all the formulas” is a terrible plan. Test constructors know you have a calculator. Questions are designed so you can’t just push buttons for an answer.
And rather than spending time programming in the quadratic formula, just learn it.