To be honest, I think I spent more time planning what age 'not' to have children - I didn't want to be a young mother and I didn't want to be an 'older mother'.
Any planning obviously counted for nothing because each of my children are much loved but certainly unplanned in the sense of thinking "now I'm going to try for a baby".
I was a new mother in my early 20s (earlier than I'd have chosen), in my 30s (when I was ready and financially more secure) and in my 40s (when I thought I was long past falling pregnant). In my 30s I was also a foster mother. There have been definite advantages associated with each age and stage.
Lots of loving, living and learning has gone into my role as a parent, but planning didn't have much to do with it.