I'm just not so sure about the time-line, though. The outbreak starts May 8th and by July 2nd or 3rd little ones can be heard in the Arena. In fact, it seems that Ink is training little ones as early as the first week of July, because Samantha tells Datu that she and Kalani were held captive around two weeks (but the time was probably shorter.) That doesn't leave a lot of time for conception, gestation and birth.

Then again, on the other hand, we see that the zombies modified by Ink have a very accelerated growth rate.