I will fly from YYZ to LGA on next Thurs(Nov 22nd, US thanksgiving day).
I have never been YYZ before and it's my 2nd time flying on AC.

2 hours before departure is enough? My flight will depart YYZ at 11AM.

I will check one baggage and need to clear pre-US immigration I guess.

In the US, thanks giving day is not a travel heavy day in general.
(+/- few days from thanksgiving are very travel heavy though)

I checked inventories by fare bucket for some usual US routes from YYZ and found that flights on Nov 22nd look better booked(especially 9AM-12PM) than next wed and fri..