Mine didn't eat anything before 6 months, but once we did start weaning we gave them a little of whatever were eating at all meal times. DD1 first actually ate something at about 8 months and DD2 managed to ingest some banana at about 7 months lol!
With BLW you just give them healthy, nutritious food from your own plate. A good balance of fruit, vegetables and carbohydrates. They also need a bit more fat than adults do and less fibre.
Good first foods are strips of bell peppers, carrot, cucumber, florets of broccoli and whole apples and pears. Strips of chicken are a good first meat and lumps of cheese are also good.
The important thing is to give them a lot of options and they will instinctively pick out the foods that provide them with whatever their systems are lacking.