You can tell the hospital that you don't want visitors until you say so, they can turn people away (as mean as it sounds...). I also suggest telling them that you will let them know when it's ok to visit. Even if they do the whole pouty, sad thing, it's your choice and only yours. They need to remember that you've just given birth, and need to spend that time with your baby and DS1 and husband, it's important bonding time for you as a family and you should be able to choose who see's you and who doesn't. Where is your DS1 going to be when you go into birth? Obviously whoever is caring for him will know, so you will need to make sure they can keep your special secret.
When we had DS1, no one knew until we called about an hour after he was born. Then they didn't come until 3 hours after that (getting them to leave was another story!). Then when we had DS2, only my brother and his wife knew i was in labour as they were caring for DS1. DS2 was born at 9.41pm so we didn't call anyone until the following morning (by 7.30am i couldn't wait anymore lol), and everyone respected our wishes and waited until visiting hours began at 2pm.
Stick to your guns, and enjoy your baby xo