I just did that in the last weekend on my 1/4 acre lawn. I used a landscape rake to spread top soil on the lawn. The landscape rake is
4-ft wide. This makes the job go faster than using a small rake. Still this took me two days to finish my small 1/4 acre lawn (around 12 hours totally spent across two days -- 4 hours on Saturday and 8 hours on Sunday).
Hiring day labors to do this probably is a better idea than trying to do this yourself in a large 1/2 acre lawn -- I just cannot see how I can do this by myself in a 1/2 acre lawn even though I am heathy and do exercise every day.
I would like to use composts. But I could not find any place locally that sell composts in bulk. That was the reason why I use top soil instead. But after seeing the top soil that they sell in bulk, I have a feeling that I might be better off buying top soil or composts in bags. The top soil that they deliveried in bulk doesn't look that great -- I should have refused the delivery; but I could not tell the difference when the top soil is wet. Hope you have a better luck buying the good stuff.
Jay Chan