Sorry to give you the bad news but at 6mo going from 6.30 to 4.30am is actually great.
The 2am/5.30 may be the start of a 6month growth spurt. So he may start taking more solids, I would start offering a 3rd solid meal in there & that may help things along, but in all honesty, I had to give Aiden his last feed at 8pm, to get him to last through until 6/6.30am until he was about 10 months old!