Generally, you can either reduce the time by about 15-25% and cook at the same temperature OR reduce the temperature by about 25-50F/12-25C and cook the same amount of time if you are converting a "regular" recipe to use in a convection oven. Make sure you have plenty of air flow around the pan(s) because that's what makes it faster, the consistent heat from the air flowing around the pans.
The results should be essentially the same (texture, flavor, inner color) except that the outside will probably not brown as much. It also might rise more in the convection oven (I find this is more noticeable in lighter cakes).
If this is the first time you've made this adjustment for this recipe or made such an adjustment for your oven, you will still need to check and make sure the bread is actually done at that time. It might still need a few minutes more.
Another way to make it cook faster is to use smaller pans. I invested in a number of mini loaf pans and now use those more often than the full size pans. Smaller loaves are more convenient in many situations. Or you can use the same banana bread batter to make muffins.
Some references with more details about converting from conventional to convection (which all say about the same thing -- for long-baking recipes, reduce time or temperature):
Further info/discussion points on the effect of temperature in baking.
There is a great, if brief, explanation of a few things that happen if you increase or decrease temperatures for baked goods using a conventional oven here, but from the point of view of "why 350?".
Essentially, if you decrease your oven temperature too much, your baked goods will tend to dry out and harden before they finish cooking, or if it is too cool but not as dramatically cool, the effects of steam or baking powder will not happen as suddenly so the result is less height, more density.
With a higher temperature, you get more quick-rise action, but of course if you raise the temperature too much, you can burn the outside while the inside is still uncooked.
Fortunately there is quite a bit of wiggle room in most recipes for cakes, quick breads, brownies, pies and even yeast breads. You could very easily increase or decrease the temperature for most of these things by about 25 degrees without a very significant change in the end result, if you managed the time correctly.
There are certainly exceptions, such as trying for a specific texture of a chewy cookie, or a more delicate, fluffy cake like angel cake (if it rises too much, it will tend to collapse).