With Kate Middleton expected to go into labor and give birth to her second child any day now, Prince William has started his paternity leave a bit early. The Duke of Cambridge completed the first phase of his air ambulance training ahead of schedule, and he's now at his wife's side in Kensington Palace. Last week, Kate spent a few days at her parents' house in Bucklebury, having a sweet play date at a local farm with Prince George. Meanwhile, Prince Harry might be back in the UK for his niece or nephew's arrival, as he's attending the London Marathon this weekend before returning to Australia on Monday. As the world awaits the arrival of Prince William and Kate Middleton's second child, see the couple's road to royal baby number two and find out where the newborn will be in line for the throne.