They could have five years between the coffin scene and the curse if they want.
For some reason I always felt that after Charming kissed Snow in the coffin that they married immediately. I’ve never thought before about the possibility of time in between that. So yeah, there could be years in between for all we know. That would be cool, plus it would help keep the Snow/Charming stories fresh and new. That’s kind of why I had the opinion that the Snow/Charming stories were over because I didn’t think about time between the coffin and their marriage.