The easiest thing is to add 0.5-1% FCS into the media, lowering the concentrations of EGF and FGF. You get differentiation in 24-48 hr with he cells fully differentiated in 72 hours.
It would be helpful if you specify which kind of neurones do you want to obtain. There are plenty of protocols published and some commercial kits that can be useful (I would recommend you to better find a protocol than a commercial kit since they are quite expensive).
And also what kind of stem cells: if you want to start with pluripotent stem cells (embryonic or iPS) or if you're starting directly with neural stem cells, if they are human or from any other source, etc. Then I guess people might give you more specific answer.
@PedroMiguelBelioMairal: I am considering both options, but probably I will start with pluripotent stem cells. And I trying to write my own protocol based on other projects, but at the end of the day, I just looking for the best and cheaper option. I really appreciate your suggestions.