The NHS recommends offering water in a free-flow sippy cup from 6mo with solid foods. I think this is mostly so they can practise sipping it though. Some LOs will want a drink with their solid foods to help wash it down and rinse their mouth though. You could of course offer a quick BF straight after the solid food if this were the case.
Remember if you do give water before 6mo though it needs to be boiled to sterilise it.