Western doctors and the baby clinic (and baby books) all advise that it is better to start giving solids to bbs when they are 6 months old. The reason is so that by that time, they can usually sit up properly so that their "sik do" ie food canal is vertical and the bb can handle the solids better. Also, bb get all the nutrition they need until they are 12 months mainly from their milk (and not solids) so that before that, we are only helping bb practice to eat. Milk is still the most important for them.
However, if your bb is big and has a big appetite, some doctors may advise you to start earlier so ask your bb's doctor to see what he says.
Re fruit juice, it is better to postpone giving diluted fruit juice until after bb is happily eating vegetables, fruits, rice, congee etc...and water otherwise they may not like to try these things once they have tasted the sweet fruit juice. (Remember to add water to the juice)
for my baby, his first meal is at about 8am (7 oz), I will rather wait for 4 hours for each meal, and I will give him a meal of cereal(4 spoons + 2 oz milk), and his last meal will be about 12pm.
I do give him some juices from Heinz(stage 1), but remeber to dilute with water(1/1).You could also start mixing the cereal with other food like vegetable/meat, it depends on your baby's appetite.
My baby loves it very much and he is about 20 pounds already..