Maybe I misunderstood your point. But I think it is a mitzva to have children, and it is not relevant how you are going to support them at all. And once you have them, if you need to take the benefits, you take them.
And I think that is the correct mindset, and I challenge you to find me a source that one is supposed to think about he is going to support kids before having them.
The question of whether one should work or not is a separate question and is the topic of other (most?) threads on this board.