According to JP Wiki, there is 4 new 4* girls, and 3 of them are from Winter Rose.
If Nutaku is following DMM schredule, the first one should arrive in 4 events, in less than 2 months.
http://flowerknight.wikia.com/wiki/Zephyranthes
http://フラワーナイトガール.攻略wiki.com/index.p...82%B5%E3%82%B9