Bella, am in the same position with my LO who is 20 weeks. Usually wakes around 5, I go in a few times ,putting dummy in etc, then he'll drift in and out of sleep, I never speak to him, stay in his room for just a few seconds, don't turn the light on etc. He's not really distressed, just moaning/chatting/shouting. Sometimes goes back to sleep from say 5.30 to 7. I always wake him at 7 no matter what (I am quite strict for a BW person really!)
I was worried by doing this I'd give him a dummy addiction for 5am, but no matter what I am not feeding him. Anyway, this morning he slept until 7 without waking up at 5, and I had to wake him. So he can do it. I think they come into lighter sleep at this point and it may just be a case of waiting until they get a bit older and they realise this is still sleep time. Fingers crossed anyway!!!!