I've been toying around with the idea of introducing solids too. My baby boy is currently only 4-1/2 months old, and also at the top of his weight class (97 percentile). So far, he seems to be full after each feed (bfing for around 10 mins). But he has been waking up in the middle of the night (around 4 am) bet the dream feed (1 am) and the first morning feed (6 am). We don't feed him when he wakes at 4 am though - we just usually re-swaddle him and occasionally rock him a bit to lull him back to sleep.
I'm told with bigger babies, they may need to have solids sooner - if only to keep up their energy levels during the day. I'm holding off for the moment (I'm hoping to keep him on exclusive breastmilk until at least 5 months) but I did buy a box of baby cereal - just in case his patterns shift and he starts to need more calories.