Board Thread:General Discussion/@comment-5792073-20160331134939/@comment-24674051-20160402004710

From the time the first curse was broken (when Emma entered Storybrooke) until Regina undid the first curse, there was not that much time. there was a couple of months between Emma's arrival and when she broke the curse so that everyone could remember. from that point it was about 3-4 weeks between the beginning of Season 2 and the middle of Season 3. (Emma & MM in EF for about a week tops, about a week with Cora while Gold was in NYC, and 1-2 weeks for Greg, Tamara, and the Entire Neverland Arc.)

So while there was time, there was not that much after the curse was broken. The more likely option is for Hades to have approached Zelena prior to the first curse. Based on Zelena's age, Oz was likely frozen in time during the curse like other lands. She was not in the EF during that time, since she would either have been caught up with the Curse, or in the Safe Zone with Cora, and since she never met her Mom, that second option is highly unlikely.