Good question. We only take our son to church right now. We cannot handle 2-year-old twins at church. Isaiah needs to really focus and follow the order of Mass. He has his own missal for this purpose. However, when the girls are there, they either disrupt him or he chooses to play with them instead of attending to Mass. I am not really sure how to handle our twins at church because we only have so many hands and we cannot leave Isaiah alone in the pew. The girls only respond to books and coloring for very brief amounts of time. We are also in a very negative phase right now. So, they shout "No!" a lot. They overwhelmed me to the point that I hated attending Mass. So, we just trade off taking our older son and go every other week.
Soon, we will need to start introducing the girls to church again. We shall see how it goes when the times comes. Just remember that no child will ever be perfect in church and it is important that they have exposure. I have a friend who starts introducing her children to parts of Mass at age 3. I believe they bring them in for the Eucharist in the beginning and slowly add in other parts until they are 5. Then, they are expected to sit through the entire Mass. The hard part is when the nursery is not available.