I started my first two on solids at 4 months as that was the recommendation at the time for formula fed babies. My first baby took to solids really quickly but my second one was a bit slower so she would have been nearly 6 months before solids became a proper meal for her. My third baby was nearly 6 months before I started her as she wasn't ready earlier and also the recommendations had changed to 6 months for FF bbaies by then too. My newest baby is also FF but I will wait until 6mths before we start solids.

I did start them all on farex, but they didn't like it so I just used pureed fruits and custards as a first food mostly.