I think it very much depends on what you want the age gap to be. Had I not been bothered about a bigger age gap I think I would have waited a little longer. But I only know this now as I know how hard it is having a child under 2 and being pregnant. I think perhaps maybe closet to age 3 when the new arrival comes would be less of a strain as we are well and truly in the terrible twos at the moment, even though he isn't 2, and it is HARD. Plus by that age they will likely be in play group, more independent, in a toddler bed and possibly potty trained. So less of a challenge when you already have a new born. I know if we do have a third it won't be until the youngest is atleast 3 possibly 4. I need to feel like me again for a while!