Baby will change their sleeping pattern gradually. They will sleep longer during night time when they grow older.
My gal is going to 3mths next week. She start to sleep longer since 2 mths old. Babysitter feed her FM during day time then I feed her EBM at night. My gal drink about 120ml at 3 hours interval. After her last feed (EBM 120ml) at around 8 - 9pm, she will sleep until around 3 - 4am then wake up for milk. Actually she change her sleeping pattern by herself, I never do anything.