Of course it's normal. And even if she did have a "schedule," it would likely change next week or tomorrow. A three month old is still completely reliant on her biological needs, he sleeps when his body demands it and wakes to eat the same way. In fact, waking only once a night is sleeping better than most infants his age. Waking every 2-3 hours is what's common at this age.
Also, how is going to bed at the same time each night, waking at about the same times each night, and waking for the day at the same time each morning NOT a schedule?