Your trivia is inconsequential to God's plan of salvation..
Any true Bible student knows that Cain could have married as many wives as he desired to..
The Bible says..
Gen 5:4 And the days of Adam after he had begotten Seth were eight hundred years: and -->he begat sons and daughters:<--
Gen 5:5 And all the days that Adam lived were nine hundred and thirty years: and he died.
THE ANSWER IS
No one knows how old Cain was when he went into the Land of Nod
Gen 4:16 And Cain went out from the presence of the LORD, and dwelt in the land of Nod, on the east of Eden.
Gen 4:17 And Cain knew his wife; and she conceived, and bare Enoch: and he builded a city, and called the name of the city, after the name of his son, Enoch.
Mean while ADAM AND EVE WERE HAVING MORE CHILDREN...AND THEIR CHILDREN were fruitful.
NO ONE KNOWS HAW MANY GENERATIONS/DESCENDENTS OF ADAM AND EVE WERE UPON THE EARTH WHEN CAIN TOOK HIS WIFE.
IN MY EXPERIENCE OVER THE YEARS
YOUR KIND OF TRIVIA ABOVE ....
IS USUALLY WHAT A PERSON WILL GO TO/ASK WHEN THEY JUST WANT TO MAKE CONVERSATION...
CREATE A DISTRACTION,
TO CIRCUMVENT THE SERIOUS CONFRONTATION ...THAT CHALLENGED THEIR UNREPENTANT HEART...
IT IS NOT PERTINENT TO GOD'S PLAN OF REDEMPTION...MUCH ADO ABOUT THE
SOMETHING PERTINENT TO REDEMPTION FROM GENESIS,
THE FIRST SACRIFICE
OF THE BLOOD OF AN ANIMAL
THAT WAS OFFERED/KILLED
TO COVER MAN'S NAKEDNESS BEFORE GOD/MAN'S SIN...
Gen 3:21 Unto Adam also and to his wife
did the LORD God make coats of skins,
and clothed them.