If you get a magnifying glass and use it to examine a bit of the bedding once it has been disturbed a little, you may see some worms that are tiny, tiny, tiny. I can't remember how long it takes for eggs to develop into worms, but it seems to take forever if you are waiting for it.
i believe i received my mix sized batch of 5,000 in early june. the oldest one's babies are, this week/last week, wandering around as beetles.