Timing a quick bread with added fruit can be a bit of a challenge. When you add fruit to a batter the moisture can be really variable and that moisture needs to cook out for the batter to set.  Make sure the oven has reached 350° before putting the loaves inside, and place them on the middle rack without another rack above them. Around the 30 minutes mark, I begin looking in on the loaves. Because the fresh fruit makes the timing variable, I am really attentive the last 5-10 minutes of baking. If the loaves are starting to brown or crack, then I use the good old toothpick method to see if the center is cooked. Poke a toothpick directly in the center of the banana bread. If it is clean, then it is cooked.