Re: Signs of readiness at 4 months old??
I am no expert, but my gut feeling is to wait a bit longer. My son was early sitting up on his own but we still waited until he was 5.5mo before starting solids. In the meantime he sat with us at meals and played with a plastic spoon while we ate.
BTW, I have seen it mentioned here a few times that the pincer grip is a sign of solids readiness, but my recollection of Gill Rapley's book is contrary to that. When baby starts solids we cut the food into long pieces because they can only pick up with their fists, not their fingers. Pincer grip doesn't usually appear until 8-10mo range.
My little man was born 12/17/2010.
Baby girl was born 4/30/2014.