Everywhere I have read its suggested as starting from 9-12 months, I think because its not such an easy taste like pear etc, rather than it doing any harm.
However I bought some which was from 4 months when I was in France which was mixed with other fruits. So if you mixed it with banana it would taste better at the start?
I had held off giving it on its own with Izzy, and now she is 9 months she is going to try it cos I love it!