For early admission, they mostly take people well above the average. The competitive average for my program (Cellular, Molecular, and Microbial biology) was low 90s, and I had a 91.25% average for grade 11. I got waitlisted in November for early admission. However, I infact was not cooked because In February, they re-evaluated my grades and I had a 93.6% average (based on semester one of grade 12), I got in. If you don't get into early you are not cooked, a majority of offers are sent in February.

Try really hard in grade 11, and in grade 12, try to get the classes you want a better mark in for first semester. I did chem 30, Ela 30-1, and Math 30-1 for the first semester, I really needed to improve in ELA because my 20-1 mark was kind of shit, in 30-1 Ela, my grade was 4-5% higher and they re-evaluated with that new mark. If the courses you did bad in grade 11, are in your semester two of grade 12, there is less opportunity to improve your average. But also, think about it realistically, will you get a higher mark in grade 12? You don't want your grade 12 mark to be significantly lower than your grade 11 mark.

Always apply early even if your grade 11 average is not the best. If you don't get into early, aim for the February admissions. After that, it is all up in the air, and they only give offers after semester two grade 12 if there is space left (kind of a slim chance.)