I have been staying home since my first was born 4 1/2 years ago and I just love it! I really didn't think I would be cut out for it, but I decided to give it one year to try it out and I just couldn't imagine going back to work after that! My daughter is in preschool and my son is in a Mom's Day Out 2 days per week, so I do all of my errands, doctor appointments, grocery shopping and large home projects (like cleaning out closets, etc) on those days. I also like to try to do some volunteering during this time. The rest of the days, we spend at the library, park, zoo or other activities and sometimes have playdates with friends. As far as a schedule, it kind of depends on your kids and their ages. You said you have an 8 month old, so I'm assuming the baby is still taking 2 naps per day. This limits what you can do if you want those naps to be at home in the crib. However, as it cools off more, you can put the baby down and then let the older kids play outside (this is key if you have a day when you don't go anywhere because they have to get their energy out somehow!). Find out what the library schedule is for story time. My kids love doing that! We miss our toddler time because it's during my kids' school time, but we still go to the library once every week or two and check out books and let them play for a little while (they have a small toddler area). Again, the zoo is great if you have one close because the kids never seem to get tired of going there. We just get a family annual membership and then we can go as much as we want! You'll have to find activities in your area, but also see if you can find a playgroup and make some new friends.
As for the housework and cooking. I make a meal plan for the week and shop to that list. That way, I know at the beginning of the week what I'm going to be making for meals and I stick to that (I even incorporate leftover night). It helps because I can take into account things that might be going on in our schedule and dinner isn't always such a chore. If we're going to be out in the afternoon and I won't have time to do any dinner prep, then I cook something in the crock pot that day and put it in there in the morning. The housecleaning can go one of two ways. You can work on a room at a time and rotate throughout the week (one room per day) or you can do it by chore (all mopping, dusting, bathrooms, etc.) rotated by day. I have heard people swear by flylady.net, so you might want to check that out. I don't use it personally, but lots of people love her!
I think you're really going to enjoy being home with your kiddos and it might take a few weeks or months, but you will find a schedule that works for you and your family. Best of luck to you!