A foot thick mulch might do more for it than tilling it in the
fall, unless you have more soil amendments that you need
to mix in (rock phosphate, granite dust, organic amendments
that need a season to break down, and so on).
See
http://www.puyallup.wsu.edu/~Linda%2...dments%202.pdf
for some surprising results with just mulch over packed, mostly
clay soil.