I'm similar to Johnny
I do not fertilise at planting time as they might put on too much lush growth which might not be a good thing if we get a severe winter.
In spring as things are beginning to warm up and there is signs of growth I give them a nitrogen feed and they usually romp away, but do not overdo the nitrogen as too much of this can effect swelling. That is the allium family do not like high levels of nitrogen at the bulb formation state, they would be better served with a potash feed at this time to promote ripening.