i dont have much to offer you ...but it's great that you guys wana have kids together. it really shouldn't matter to you or your wife what age you are when your kid grads from HS...all that should matter is that it's your kid.
personally i don't think there are any ways to make it happen quicker or faster, if it's in the cards for you, it will happen...
and you my friend, are definitely playing an awesome hand by wanting to have one in the first place.
i wish you and your wife all the best and i hope everything works out for you two...because seriously, there's no greater gift...but i bet you already know that