When should I start preparing?

Clare
I'm very eager to start a family in a year of even sooner if things go well, and I'm not sure when I should actually start preparing? (Seeing my GP, taking pregnancy vitamins and such). I'm 22, 23 in January, and I'm at university. My partner and I have been together for nearly 2 years, and knew each other before that. 
We're awaiting him getting a graduate job, for which we'll be moving out. 
Of course I'm a little more keen to have a baby, but he'd like to have one within 2 years as well (me on the other hand, maybe sooner! 😛) 
So when did you ladies start preparing?