Well, traditionally the answer is today in 1464. According to some versions of the story Edward IV happened upon Elizabeth Grey (née Woodville) under an oak tree near her family home in Northamptonshire where she played the damsel in distress card and petitioned the king for help in reclaiming her son’s inheritance. Taken by her beauty, Edward tried to make her his mistress and when she refused, he married her, kept it to himself for five months and then dramatically announced it at court when his cousin and first councilor, Richard Neville, Earl of Warwick, was pressuring him to marry King Louis XI of France’s sister-in-law.
But there are some problems with this narrative. First, the whole oak tree imagery is a bit over the top. Second, the date of May 1 or “May Day” is very romantic, but the very fact that it is romantic should raise some eyebrows. Third, there is clear indication from events in the summer of 1464 that there was no plan to present Elizabeth as queen. And four, it is unlikely that Edward and Elizabeth only met for the first time that year.