Definitely set the ground rules now before people start getting ideas about waiting outside the delivery room etc. If necessary you can soften the blow by saying that if you feel fantastic and can't wait to show the baby off you'll revise your stance (but of course that's just your Get Out of Jail Free card).

You can also ask the midwives to act as bouncers if necessary.

You may also want to consider not telling anyone you are in labour if you think there is a risk people will show up anyway. And you may also want to consider whether or not you want anyone around when you first get home (ie do you just want it to be you and your DH and the baby for the first day as a brand new family - that's what DH and I wanted) - in case everyone descends on you as soon as you get home.

Just make sure you and your DH show a united front on this one so nobody can "get around you" IYKWIM.

Waiting 24 hours is a great idea. So many first time mums I know have complained that they were so inundated with visitors they felt that they got hardly any time alone with their newborn, felt under pressure to finish breastfeeding before visiting hours started. Those first few hours are so precious and you will never get them back. It's not going to kill anyone to wait a few hours before they get to cuddle the baby.

Sorry - I've worded this a bit strongly I think...please understand I am coming from a "once bitten, twice shy" perspective LOL.