Black Australorps 20 weeks, should they be laying?

[crayon]

We got black australorps December 3rd and then Dec 9th- Some of them are SOOOOOO small. Well actually MOST of them are super small. Like they look like they are maybe 2 months old- not going on 5 months.

I have not seen any mating with the roosters yet, although my roosters are getting big and red now. I found one small egg today- I think it was a banty egg, but it got me to thinking, they are now 20 weeks, they should be laying anyday- but they are so tinny I can't imagine them being ready yet.

Any advice?

 

[sourland]

Can you post pictures? Any comb enlargement and reddening in the pullets? 20 weeks is a little early.