Timing feeds, 6 week old

FTM and I'm not sure if I'm supposed to still be timing his bottles? It's always 4 hourly but when he goes over that I freak out. He's a big boy, he was 8.7 pound born and over 9 pound now and drinks 100mls everytime but is he allowed to go longer than 4 hours? I'm so confused because at night he will easily go 5 or 6 hours sleeping then want his bottle do I let him do that during the day?