A baby as small as 1200 grams and even smaller can start at the breast as soon as he is stable, though he may not latch on for several weeks. (breastfeedingmums.com)
As you might already know, breastfed babies need to form a good latch onto the breast for effective feeding and tongue - tie could interfere. (bounty.com)
I don't like that there's only one latch system on the rear seat though, and there's not a good place to connect the rear strap without blocking the luggage area. (autolist.com)