Excellent analysis Bhai MB Singh jeeo and thanks for starting this topic.
You assumed that there is one Jyot-Vigaasi in about half a million population and roughly 2 for every million but Gurbani says:
ਕੋਟਨ ਮੈ ਨਾਨਕ ਕੋਊ ਨਾਰਾਇਨੁ ਜਿਹ ਚੀਤਿ ॥As per Gurbani stated above, one in many crores (1 Crore is equal to 1 million) is such in whose heart Vaheguru resides i.e. is a Pooran Gurmukh. So if we assume that many crores means 10 crores, then it would mean that there one Mahapurakh for every 100 million people and if we assume that "many" means about 100 crore, then it would mean that there is one Mahapurakh for every billion people. The world population is about 7 billion. As per the analysis done above the number of Mahapurakhs would be as follows:
One Mahapurakh per 100 million would mean there are 70 Mahapurakhs in the world.
One Mahapurakh per 1 Billion would mean that there are 7 Mahapurakhs in the world.
The minimum Gurmukhs required for an Amrit Sinchaar Samagam are 7 Gurmukhs - 5 Punj Pyare, 1 Granthi and 1 Pehredaar. It seems likely that the total number of Mahapurakhs would have to be at least 7 and maximum around 70.
Now, Gurbani says that one Mahapurakh can purify the the whole town through His (or her) individual Naam Abhyaas Kamaaee. In order to totally turn the tide against Kalyug, it would be necessary to have about 70 Mahapurakhs because I am assuming that there are about 70 big cities in the world.
I am not saying that one Mahapurakh can't purify the whole world but there is a Pankiti in Bhagat Kabir jee's Baani that goes as follows:
ਕਬੀਰ ਸਈ ਮੁਖੁ ਧੰਨਿ ਹੈ ਜਾ ਮੁਖਿ ਕਹੀਐ ਰਾਮੁ ॥ ਦੇਹੀ ਕਿਸ ਕੀ ਬਾਪੁਰੀ ਪਵਿਤ੍ਰੁ ਹੋਇਗੋ ਗ੍ਰਾਮੁ ॥੧੧੦॥(That mouth/face alone is blessed through which mouth Vaheguru is utterred. What to talk about the body, the whole city (where Gurmukh resides)becomes blessed)
From this Pankiti I deduced that normally where a Gurmukh resides, that whole city becomes purified and if 70 Mahapurakhs are residing in all different cities of the world, then surely the whole world would become purified and this would result in multitudes of people engaging in Naam Abhyaas. What a great sight it would be to behold.
Bhul Chuk dee Maafi jee.
Kulbir Singh