Wait another week. Per Michael Bush's "Bee Math" it can be up to 33 days for a new queen to lay eggs. She may just be starting, within a week you should be able to see larvae. Don't be in a hurry with splits.
Also....they don't emerge and then immediately go on mating flights. Usually about a week to mature. If I heard a queen piping....I wouldn't be worried.Right after she hatched out we had about 5 days of rain and cold wx.