James Madsen was born in 1973 which makes him today 36, when he was in x-men 1 he was aged, 27 - Tim Pocock - who plays young Cyclops in wolverine was born in 1985 which makes him 23 - Now bearing in mind that the actors tend to play the characters near 3 to 5 years younger than they actually are, that means the character of Cyclops in x-men 1 - 3 (all three movies taking place within a year in story continuity) So we are lead to believe that Cyclops is (25) its just a guestamation but i think its near enough. Now Cyclops in X-Men Origins Wolverine, althought the actor is 23, he was probably playing a Cyclops aged 18/19 - so baring that in mind, we can sum up that the amount of time between X-Men Origins Wolverine and X-Men 1, is not 15 years but only 5... also bear in mind that X-Men Origins Wolverine im told your not really told how long ago the last part of the movie took place, but we were only told it was 15 years. So as its not stated 15 years in the movie, im saying its a better guess to say it was only 5 years...
Now saying that x-men origins First Class will probably be the next thing made before Magneto so First Class will take 3 years to make, in that time the actor of Gambit Taylor Kitsch who is currently aged 28, by time First Class comes out he will be 31... and as they are all playing characters younger than there real age. you can probably reuse Taylor Kitsch as Gambit in X-Men 4, because the young characters that became x-men by the end of the first movie will be only slightly younger than what Gambit would 5 years later. Plus it wouldnt take alot to age him slightly but i dont think we need it.