I think that this is probably after the Queen kill’s Snow’s father because the Queen is wearing black and before that she didn’t.
Also Rumpel had the lamp and i think that Regina could only look through the mirrors after the Genie got trapped, but you are right that we don’t really know that.
I would also say that this is after the Queen tried to kill Snow at least the first time, but i don’t really have a reason for thinking that.