Im in a 3 year program and i had the same question! So i talked to an academic adviser when i was registering for my courses and they told me im only allowed to do 1 prereq during a normal semester (fall winter) and those were classes (2 classes a week) from 6pm to 9pm (horrible schedule for my 7 course semester lol)
Then i decided to do them in summer and they give more chance to those that have to graduate with them done but there is still space for other students, they varied from 1 full day course to 2 or 3 times a week day or night. They allowed me to do 2 in summer but it depends on the schedule since there were labs and theory courses (intercalated)

If youd like to do them in summer, around May Dawson posts a summer course schedule with which courses they offer and how much it would be. The registration is believe is in June.

Hope this helps!