I've been curious about this for the past weeks and asked friends and family and had also been leaning to wait until 6 months and then I read something that really made sense on https://www.askdrsears.com/html/3/T032000.asp:
How will I know when my baby is ready for solids?
As with all aspects of parenting, watch your child and not the calendar. Besides the developmental milestones above, watch for these ready-to-eat cues in your baby:
* Able to sit with support, reaches and grabs, and mouths hands and toys
* Watches you eat, following your fork as it moves from plate to mouth
* "Mooches," reaching for food on your plate
* Mimicks your eating behaviors, such as opening her mouth wide when you open your mouth to eat. Grabbing your spoon is not a reliable sign of feeding readiness, since baby may be more interested in the noise, shape, and feel of your utensils rather than the food stuff on them.
* Baby can show and tell. Around six months of age babies have the ability to say "yes" to wanting food by reaching or leaning toward the food and "no" by pushing or turning away. Expect mixed messages as your baby learns to communicate. When in doubt, offer, but don't force.
Does baby seem hungry for additional food? If your baby is content with breastmilk or formula, no need to complicate his life with solids. If, on the other hand, your baby seems unsatisfied after a feeding, is shortening the intervals between feedings, and several days of more frequent feedings don't change this, it may be time to begin.