i inquired about a transfer from chem eng. to nanotech after my first year. they replied that an average in the 80's was required... that was a couple years ago when the program was in its first year. though, it may give you a rough idea that the fraction of the class that probably had 80s after my 1st year was probably around ~25/140.
regardless, my suggestion would be to contact the office of first year engineering. yes, that is indeed a specific office for anything pertaining to first year engineering. I'm sure it's possible, but i don't know what the criteria would be since you'd be transferring from the sci faculty and not within the eng faculty.
a good point was made about planning out your courses. if you're really determined check the undergraduate calendar to compare the 1st year nano courses to see if you can take the antirequisites in your 1st year. though there is the rare case that antireqs aren't listed. for example, my che 102 course allowed me to be exempt from chem 120 & chem 123.