While my main focus in the garden is butterflies, I also like to encourage hummingbirds to come and visit. Hummers like to use many of the same flowers that butterflies prefer, so it’s really easy to get them to come and visit.
I also like to put up feeders, but then the question is , “What date is the best?”
If you go to the website http://www.hummingbirds.net/map.html, it will show you exactly where the hummingbirds are and help you predict when they will reach St. Louis.
Butterfly Gardening 
because we are so north of this map I am guessing april or may. We see them in large numbers by then
On my calendar I have a reminder to put them out on April 19th. We’ll see how accurate that is.
Thanks for posting this map.