Gradually increase the length of time until you are able to write for about 45 minutes, and then you can begin alternating that time with 15 minutes of rest. (nextscientist.com)
Take a break or alternate the time when each of you cares for your baby. (kidsmatter.edu.au)
As a starting point, I would suggest posting twice daily, alternating times of the day to find out when your highest engagement occurs. (entrepreneur.com)