The earlier you can get your feeders out, the better chance you will have some nest nearby. Depending on the temps, I try to put my feeders out toward the end of March. This is when (in my area) the males start to arrive. Then roughly two weeks later the females start to show up. If they know there is a constant food supply available, they are more likely to make your place their home for the summer. I use six feeders to keep the fights down, but there is always one bully that thinks every feeder is his.
DSC_0057 by
schabefrank, on Flickr
DSC_0052 by
schabefrank, on Flickr
DSC_0017 - Copy by
schabefrank, on Flickr
If you are looking for a plant that really draws hummers, and butterflies in.
Try planting a few (
Cuphea ignea) 'Cigarette or Firecracker plant' I had four planted in a small raised bed in light shade. They grew here to about 2 1/2 feet high, but do not survive our winters, so for me it's an annual, but well worth it imho. Never a day went by that I didn't see at least three feeding on them at the same time.