I had 2 big babies, both over 8kg at 3mo... neither really fitted the 4hour routine, the first because he simply didn't cope with more than 1.25/1.5hours A time & the second because well I was juggling his life to fit the 2 children having a big nap at the same time... I wasn't giving up a big 3hours break in the middle of the day so we had more like 2.5/3/4.5/3 routine with DS2, also he'd had a hospital stay that threw out my milk supply (he was on IV fluids)
Anyway I think you kind of have to work out what is best for your child, if she sleeps well then see if it gets to say 3.5hours, it doesn't have to be exactly 3 or 4 sometimes you can do a short A time first eg an AEASAEAS to fit it in better... just as long as they don't fall asleep on a feed.