It wouldn't bother me if a neighbor started mowing with a gas mower at 8am, but the lots in our neighborhood are largish and there are a lot of trees that dampen the sound. I rarely hear people mowing in my neighborhood if I'm in my house.

My sister in law who lives in a new subdivision in Texas where the homes are so close that you could probably pass things back and forth through the window to you neighbor on the left and right. If she were to mow early I'm sure the neighbors would hear it very well and be very annoyed.

Also probably depends on your immediate neighbors and how they feel about it.