Help with sleep please!

Hiya, I hope someone can help! My 1 year old has always been a good sleeper, at the moment he has a morning nap 10-12noon and then goes down to bed at 6pm. He sleeps through until 5.15-5.30am and I can’t help thinking this is too early for him to wake up!

Some friends have sought help from a sleep consultant who said to leave baby in their cot until 6.30-7am, we’ve tried this but he works himself up and starts getting very upset (and loud!).

Does anyone else have any other tips to help or suggestions for helping him sleep a bit longer in the morning?

Thanks 😊