You can vent sex them when they get older... maybe 8 weeks old...
You have to be very gentle and know what you are doing though...
Also... its pretty cool that they hatched a chick by themselves! Most buttons dont go broody very well...
Arent they the cutest little things when they hatch?? About the size of a dime... :o)
From what I'm reading the males in adult plumage will have more intense coloring on the chest, often with a white bib. Females are more subdued coloring. They reach sexual maturity at 3 - 4 months but I haven't found out when they molt into their adult plumage. Depends on their breeding cycle I suppose. I doubt that they take 5 years to attain full adult plumage like a Bald Eagle. Most likely it will be in their first full molt of the year.