You should offer a second breast after they are done or seem to be done with the first breast.
Signs that your baby are done with the first breast and are ready for the second breast include.
Letting go of the breast on their own.
Seeming drowsy or falling asleep.
The baby doing a series of butterfly sucks instead of deep sucks.
When breastfeeding your baby you should offer one breast per feed and don't swap sides of breasts unless your first breast feels very soft after your baby finishes feeding from it.
If your baby does want a top up feed within 1 hour, then you can feed again from the same breast.
However if the baby is still hungry after the first breast is finished then you can offer the second breast.
In the first month of the babies life, most breastfed babies may be satisfied with only one breast.
Although if your baby is well attached and sucking effectively, they will keep feeding for as long as they need and then come off by themselves or fall asleep.
Your baby may or may not want the second breast which is okay.