Hi there,
I would definitely not give your son any juice. I know the temptation is strong and we all think juice is so good for us, but it is really just a lot of sugar. You don't want to set up your child's digestive system and life-long habits to include too much sugar.
There is a great book about developing a baby's nutritional intelligence from the first bite of solid food on.
It's Feeding Baby Green by Dr. Alan Greene.
I highly recommend it.
My son is almost 6 months and I am just beginning solid foods. This book has been very helpful.
Good luck....