They weren't my biological children, but I took care of five kids between the ages of 2 months old to 12 years old. The ages were 2 months, 2, 6, 9, and 12...and they were all boys except for the infant.
It was very hard running after the two year old and a twelve week old puppy while trying to keep everyone quiet enough so the baby could sleep...I'm not going to lie to you about that. Getting ready for a walk was a twenty minute process and by the time everyone was ready someone had peed on themselves and the process started all over again.

I can't count how many times phrases like, "Luke! Don't chew on the dogs' bones..." "Finn, that's not your toy..." "No, don't give the baby's bottle to the dog..." came out my mouth during the day. By the time my husband came home from work to take over so I could pee by myself, I wished I had a kennel to go into and sleep! Both Luke and Finn had inuries caused by each other; Finn scratched Luke across the back and it bled in a rambunctious game of fetch and chase...Luke bit Finn on the ear after Finn stole his toy...and Luke wasn't allowed to play with Crayons and Play-Doh while Finn was out of the kennel after Finn ate the crayons that fell on the floor and Luke fed Play-Doh bones to Finn.
At the same time, I wouldn't have done it any other way. Now, Finn loves kids. He lays down calmly and nicely to allow kids to pet and love on him. He doesn't chase or knock them over, he moves calmly and slowly around them. His 'leave it' is impeccable and he does it every time. The kids have a love for dogs that you wouldn't believe. Each one got to participate in the training and care and they all learned something about how to train dogs and how to deal with them.
As long as you go into it understanding that it isn't going to be perfect, it's going to be hard work and some nights you're going to pull your hair out and wish that you never decided to bring a dog into your life, when your kids are older and you are looking back on their younger days, you will smile fondly of the memories of the day when you bathed your pup and kid at the same time because they got into the finger paint.
Good luck with whatever you choose.