This answers your first question, but does not necessarily answer your second. That would depend on whether the Maya years correspond with the Gregorian years when it comes to turns.
1.0.0.0.0 November 13, 2720 BCE
2.0.0.0.0 February 16, 2325 BCE
3.0.0.0.0 May 21, 1931 BCE
4.0.0.0.0 August 23, 1537 BCE
5.0.0.0.0 November 26, 1143 BCE
6.0.0.0.0 February 28, 748 BCE
7.0.0.0.0 June 3, 354 BCE
8.0.0.0.0 September 5, 41 CE
9.0.0.0.0 December 9, 435
10.0.0.0.0 March 13, 830
11.0.0.0.0 June 15, 1224
12.0.0.0.0 September 18, 1618
13.0.0.0.0 December 21, 2012
These are the only ones that really matter.
Assuming that there's some trigger point (not the beginning of the game), then it's really only from the 3rd or 4th B'ak'tun to the 13th that would matter (about 10).
There's also 7ish Great People in the game.
So, yes, if you hit the 'trigger' very quickly, you'd likely get more early game, due to the date->turn size conversions, but late game the date->turn size is fairly small and therefore you'd get less, or more turns in between.
Assuming of course any of that was actually triggered on the b'ak'tun and the guy didn't just happen to randomly get the bonus for another reason.