I think my best bet is to figure out where the game clock offset is, then try to find the migrants offset when the game pauses for new migrants. Otherwise it's storing dwarf wave information as a separate file / settings in dwarf therapist (not at all ideal)
Calculated my starting year to 0x06021600. No reference within the creatures-vector.
But found the value at some places:
Found '' (00160206) = 0x0043f94c (uncorrected:0x0043f94c)
Found '' (00160206) = 0x0ae27fff (uncorrected:0x0ae27fff)
Found '' (00160206) = 0x0ae32fff (uncorrected:0x0ae32fff)
Found '' (00160206) = 0x0ae35fff (uncorrected:0x0ae35fff)
Found '' (00160206) = 0x0ae47fff (uncorrected:0x0ae47fff)
Found '' (00160206) = 0x0ae62fff (uncorrected:0x0ae62fff)
Found '' (00160206) = 0x0ae88fff (uncorrected:0x0ae88fff)
Found '' (00160206) = 0x0ae95fff (uncorrected:0x0ae95fff)
Found '' (00160206) = 0x0ae9dfff (uncorrected:0x0ae9dfff)
Found '' (00160206) = 0x0aeb08bf (uncorrected:0x0aeb08bf)
Found '' (00160206) = 0x0aeb8fff (uncorrected:0x0aeb8fff)
Found '' (00160206) = 0x0aec0fff (uncorrected:0x0aec0fff)
Found '' (00160206) = 0x0aec3fff (uncorrected:0x0aec3fff)
Found '' (00160206) = 0x156656f7 (uncorrected:0x156656f7)
Found '' (00160206) = 0x15c46137 (uncorrected:0x15c46137)
Found '' (00160206) = 0x2b8f5aa3 (uncorrected:0x2b8f5aa3)
Looking at the raws it seems like at 0x0ae* are stored historical information according to my fortress and world.
I would say the game does not track the arrival of the dwarf within the structure in the dwarf vector but in aspecial history-vector. But I didn't find references...
I also found:
H
0x0aacbdc0 | 65 20 61 72 72 69 76 65 64 20 61 74 20 4c 69 6d | e arrived at Lim
0x0aacbdd0 | 83 72 69 64 65 6e 20 6f 6e 20 74 68 65 20 31 73 | 83riden on the 1s
0x0aacbde0 | 74 20 6f 66 20 47 72 61 6e 69 74 65 20 69 6e 20 | t of Granite in
0x0aacbdf0 | 74 68 65 20 79 65 61 72 20 32 35 31 2e 20 20 5b | the year 251.
...but this seems to be just a string with my displayed thoughts an preferences.