[@MelonHead]I am of a generation that closely monitored preps. Preps, in my experience, generally take at least a turn, or a whole phase to mature, and require some kind of extra mentions to let it be known a prep is cooking. 

Edit: Depending on the community, there were also limits on the number of things that could be prepped at once. I'm pretty sure that since Eden era is phase-centric, you get a single prep a turn.