There is more to mulch than meets the eye! Sure it can make a drab yard into fab yard and a landscape look professionally manicured BUT that is only the beginning. When laid down properly, (no more than 3 inches) Your plants, trees and shrubs will have better chance to harden up for the Northeast's winters brutal cold.
If you are thinking about doing any more plantings fall is a great time to do it! The ground is still nice and warm from summers heat and the rains have definitely made the soil nice and moist! The roots will settle in and gradually as it cools with Fall's cooler weather. Placing mulch around the trees and shrubs will not only keep moisture down but also vitamins and nutrients will also seep down as you water. As Winter settles in, that layer of mulch will insulate the plant and the trees roots have that extra protection.
Spring time is the time to replace mulch that has aged and needs revitalization. Snow and heavy rains will wash a small percentage away, so a spring inventory will need to be done to see what needs to be replaced.