Newby to BYC, first egg ALREADY?

Hi all - I'm new to BYC. We started raising chickens with last year with a "hand-me-down" starter flock of 17 BO hens and 2 roos (yeah, we kept Roo-2 around.) We got more confident and decided to try chicks this spring. We ordered 25 and rcd. 27 (mix of EE's, black australorp, partridge rock, white leghorn, and SL wyandottes). All are hardy and healthy other than one cross-beaked EE who is holding her own. They are 14 weeks old today and have recently begun showing interest in the nesting boxes. Today, I found an egg that looks quite different from the tan BO eggs. It's medium sized, light pink, and has a very pebbly texture. Could it really be one of our pullets has laid her first egg already? I was expecting more like early October. Also, I haven't had a chance to review old posts, but what suggestions do you have for knowing who is laying when you have a mixed flock that uses the same boxes?