DD1 didn't go down to one sleep until 18 months but DD2 went to one at 11 months. Her afternoon sleep was never more than 20-30 minutes anyway. She sleeps for 2-3 hours at 10am (she wakes about 5.30am though!). See if he goes ok with the one sleep. They do get a little cranky during the transition to one sleep but it's worth working through it. Good luck!