I won't want to have another kid at 40...

Just 1 is a lot work already. Can't image 4 at 40 and still doing full time job. When the last one go to college, it is about time to plan for retirement. If you get paid a lot then financially it is ok. My father always say back then, he is the only one working in the family and 4 kids, everything turn out good. At the beginning it is going to be a lot work, but at the end it will all worth it. Personally I like the idea of having more than 2. But I just don't think I can over come the hard periods. It is fun with 4 kids when everybody grow up. That is for sure.