You can look at the first and last line of msglog.txt, for example my character Nousia:
first line:
(143270):1bg8:[#]{06DF0653} | Zooming in ...
last line:
(008000):pcgb:[=]{06EA06A9} | Your character has been saved.
"1bg8" and "pcgb" is the key here, the format is day-month-year-hour, and the numbers start using letters after 9, so I started the game on the 1st day of the bth month (11th = November = Dead month) of the gth year (16th - the character is 16 years old) at 8am, and now it is the pth day (9+16 = 25th day of the cth month (12th = December) of the same year, and it is b o'clock (11am).
My character Pekka started on the first of April (swidden) year 16
(143270):14g8:[#]{06700281} | Zooming in ...
And now it is the 17th of November (dead) of the same year
(008000):hbga:[=]{06080060} | Your character has been saved.