My boys (31 weekers) are now 6 months old!! At their last check up they were in the 1st percentile for their corrected ages.. We have another check up on Monday so it will be good to see how they are growing now.. We went on a looooong holiday- 4,600 Kms in the car- and the boys were amazing travelers! They did get gastro while we were away and spent a few hours in hospital due to slight dehydration. 
It's amazing how fast they grow!