I've had a mix result on the outcome of crests. Some I can tell on day one that they will have a crest, some not until a month does a crest start to grow.
Also, if you look at my pics I posted above, you can see that my hens have waddles, but have different tail feathers and underbody development of feathers then my roo. The crested hens when younger can be difficult to sex until they are a bit older.
Great lookin hen. She has small wattles and her tail feathers tend to point down, versus a roos that will stand up almost at 60 degrees or so, and the biggest indicator a fluffy bottom. She's beautiful
Here's pics of my SF's. My first line of red and blue SF.'s I have another line I'm working on, another gorgeous roo that is more of a milleu fleur color (straight combed).