Most 3 month old babies will need to nurse between 6 to 8 times per day.
You should nurse your 3 month old baby at least 6 to 8 times per day and feed them breast milk of at least 5 ounces every time you breast feed them through the day.
The baby will let you know when they are full by pulling away from the breast and when they do pull away then you know they are full and need no more breast milk.
When the 3 month old baby is hungry again they will usually cry to let you know they are hungry.
But you should try to offer the breast and try to breast feed the baby at least 6 to 8 times per day which is good enough for most 3 month old babies.
But of course if the baby is more hungry then breast feed the 3 month old baby as needed.
You'll get the hang of it eventually as parenting is a learning process.