I would agree with JFG. Japanese millet tolerates flooding; that doesn't necessarily mean that it performs best when flooded. As long as the millet is not drought stressed it should produce just fine. I doubt you have time for the milo to make. Several years ago I planted jap millet, Egyptian wheat (essentially a tall sorghum/sudan grass variety) and WGF sorghum on July 7th. It grew extremely well (picture taken 10/2 of that year) until we had a killing frost on 10/31. It had fully headed out but did not make hard seed.