(If my guess is correct)This theory is about "the one's who carried will before roger and after void century"

This must be the plot"if one who inherit the will appear the next one will appear in half of the time " keep this idea in mind and start reading

First one must be joy boy who traveled in void century who was the first one to inherit the will if I guess. Because the word joyboy mustn't be his original name

.There is a catch that he is the ruler of ancient kingdom, and ancient kingdom (ancestors of d tribe) is a pirate kingdom where all race co exists. So joy boy is the title given for the Ruler of and kingdom so it is equal to modern day's pirate king

Joy boy = pirate king

Here what the catch next inherited in half the time of joy boy 400 years before Montblanc Noland . He is free spirited adveturer with good deeds (pretty much like other D) He might be an hidden D (just like Trafalgar D water law) or someone who is inherited the will "(he mustn't be blood related to inherit the will)(plus we seen it so many times before)Roger -luffy (not ace) dragon-sabo(not luffy)" he just like roger ,luffy who like to do adventures .

Remember this ship falling from the sky at start of sky Island saga , if you remember correctly they said it 200 years ago (half time of Montblanc noland) they it was a famous travel shop "st briss" 200 years ago (oda gives accurate time and date of the ship) if my theory is correct captain of this ship must inheritrer of the will "might be an unknown or yet uncover D just Jaguar D Saul and portgas D rogue"

Next one might be rocks d xebec or someone lived (probably from monkey D family) in his time who inherited it to roger ,so rocks might have killed him , so roger and garp joined hands to kill him.

And to save the world.

Next one is roger one who inherited after 50 years (basically the half time of previous one) , so I don't need to talk about it much but regarding roger because he was so close to achieving it

Next one is luffy , in pre time skip oda mentioned 22 years ago roger was executed exactly one year before he became pirate king and after time skip 2

Years passed . So now luffy completed Roger's half time (25 years) so he might become next pirate king any time soon!!!!

In the end it just a theory but it seems so well with the time oda gave us .

Follow and give me support for more theory!!!!!

Thank you