It's really up to you.
We were alone for the first week, during which DP took his first week of paternity.
My parents came over every day the following week when my DP went back to work. (They didn't stay overnight - they live an hour away but didn't want to be a nuisance!)
The third week, DP took his second week of paternity, so we spent that together, without anyone else.
ILs only popped over a couple of times, and didn't stay very long.
What you have to watch out for is people's differing idea of "help".
To some people, "help" for a new mother means letting the mother bond with her new baby whilst said visitor does a bit of washing up/laundry/makes tea etc (this is what my mum did, and I was so grateful - it meant I was on top of the housework for when we were on our own again).
Other people, though, think "help" means THEM having the baby, whilst you run around doing all the housework. For various reasons including exhausion, post-birth discomfort and a need to bond with your baby to name a few, that's probably not what you're going to want to be doing in the first few days of your child's life. So just beware of those who think helping is "having a go" with the baby whilst you entertain/pamper them.