The best time to blow off your leaf would be any time, starting from 9 AM up to 7 PM. There are some cities with bylaws that dictate how early one can use motorized yard tools and equipment. If you realize that your blower is making too much noise, you can update it and reduce the noise resulting from worn parts. This way, your will neighbor will be at peace with you. Newer models have significantly reduced noise and, in fact, have in the built mechanism for noise reduction.