My boy is more than 6 months and I still can't get him to space out the feeds to 4 hours (despite what Save Our Sleep says - I was trying to work towards that routine but never got there). I basically demand feed and he still wants feeding 3 hourly. I'd guess Ava wants feeding a bit more often too - maybe work towards the 4 hourly thing slowly (eg 3 hours one day, 3 hours 10 mins the next etc) if you want to do the SOS thing