This morning K didn't call out for me until 5.19am (the clock was set for 5.15am). I was asleep before this obviously, so I'm not sure if he woke up before that and then didn't cry out for me until after the clock changed, or if it's just a fluke that he didn't wake up until then. He was up a lot in the night (he has a head cold) as well, which can sometimes make him sleep in a little later than normal.
Therefore, I'm not assuming that he's now a trained sleeper (in fact I'm not sure there is such a thing unless you have a robot for a child), but I am pretty happy and hopeful. If he can consistently stay in bed until after 6am I'll be over the moon.
*yawn* Now, where's my cup of coffee gone?