Over-wintering get some nitrogen (BFB for me) in Spring, and a bit of bonemeal a couple of weeks later....
Normal onions get chicken pellets and BFB when I plant out (I don't really use sets, it's seeds all the way for me) but don't really need manure unless your soil is pretty ropy, some more BFB as a topdress in May.
Leeks as per normal onions, shallots and garlice as per O/W onions...
chrisc