Early rising can hit at any time and be really difficult to resolve. However, here is a simple method that usually takes around 3 nights!
If your baby is between 12 months and 3 years, the best way to reset their body clock is to reduce daytime naps by 75% and put them to bed 30-60 minutes later than usual for 3 days. They may need an additional 10 minute catnap to get them through the afternoon and this is fine but keep it to 10 minutes. (Do not attempt this method if they are under the weather, coming down with a cold or already miserable with teething.) During these three days your angelic baby will become very over-tired and grumpy and it is unlikely that they will sleep any later on the first two mornings. Do not despair because by the third night they will be so exhausted that they will sleep later in the morning.
On the fourth day bring bedtime back to your desired time, but please be realistic about how many hours your baby can sleep in one night, usually 11-12 is the maximum. You can then gradually bring the naps back 15 minutes per day by adding 5 minutes to the shorter nap and 10 minutes to the longer nap if they have 2 or 10 minutes per day if they only have one.
Please feel free to call me to talk it through if you want before you go ahead with it.07977 462252