That is very personal, only you and your nursling know.
My toddler is a month and a half shy of her 3rd birthday and still nurses. And based on her behavior, no end is in sight.
From a biological stance, it is normal for human infants/toddlers to stop nursing between 4 and 7 years. But, of course there are exceptions. You've got to find out what's right for you (and nursling).