Here are some signs of needing to transition:
1. Not taking as much at a feed (baby not as hungry at 3 hours)
2. Erratic Night Wakings
3. They are extending their awake times
4. Starts taking 45 minute naps
It sounds like he may be ready for one. Sometimes botttlefed babies can go to a four hour routine sooner than recommended. You may want to try a 3.5 hour at first and see how that goes.
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And as I mentioned in other posts, be ready to tweak, tweak, tweak
