I use Memorial weekend as the deadline to try and have all the warm weather plants/seeds in.  This year I jumped the gun a little due to the warmer than normal weather.  The birds and especially the squirrels went to digging right away.  Decided to water the next day only to find little holes dug around the tepee branches and some of the unearthed seeds sitting there, even with the really fake owl I placed out to keep the rabbit away from my lettuce and soon to be replanted spinach.