How to check banana bread to see if the bake is done.
After baking in an oven already preheated to 350 degrees for 35 minutes, open the oven and insert a toothpick into the center then remove and see if any batter is stuck to the toothpick.  If the toothpick is clean then remove it from the oven, if not then close the oven and check with a clean toothpick again in 7 to 10 minutes.