Wait. 6 mos is the recommendation for solids or any kind of alternate drink besides bm or formula. We are doing baby led weaning and I don't see the point in giving a baby juice (unless they were constipated or whatever). I'd give my kid water over juice. So when my dd can grab her own chunks of food and eat it that's when she'll start solids.
No need to rush solids, and there's really no need for juice. It doesn't offer anything that she can't get in something healthier,like fruit and water when the time comes. If you want LO to have the healthy habit of drinking plenty of water, don't give juice.