However much s/he wants. - that's probably not the answer you're looking for sorry! - but each baby is so different and there's no set rule - just as long as your baby doesn't sleep so much in the day that they're wide awake for too long at night.
The best thing you can do at this stage is put them down when they look sleepy and not count how much sleep they've had. They tend to settle into their own pattern by around 12-14 weeks.