On Goobues and Timelines.

[Anonymoose]

I'm not sure about Thancred's exact age though as it was more Gridania's 1.0 story I was taking notice of, so Professor Moose or one of the other 1.0 loremasters would be better to answer this question

My math says ~17 for both Thancred and Y'shtola in the 1562 Echoes, fwiw.

1562 - Goobbue Incident / other 1.x Echoes
1572 - 1.x / Calamity
"1577" aka "5th Year of the Seventh Umbral Era" aka "1st Year of the Seventh Astral Era" - Start of ARR through "Today" (on paper only; you're free to decide for yourself how long it's been)

The OP timeline accidentally combines the year of the Calamity and the year ARR starts into one "1577" label, skipping 5 years and landing Thancred at 12 instead of the correct 17 and Ascilia at 7 instead of the correct 12. All presumed oddities appear to be snowballing from that one point.