Hey! So as far as I know they look at the most recently completed 5.0 FCE at the time you apply (so for you, I assume this would be Winter 2020, Fall 2020). I did my undergrad at UofT and will be going there for nursing as well, at the time I applied I had already graduated and finished the UofT pre-reqs, so I'm not sure what the conditional offers are like. One of my friends who got accepted to UofT was just told to complete the pre-req she was doing by July 15th.
I did apply to Nipissing & Queens as well, and for those I enrolled in an anatomy course that was a pre-req. I got accepted to both with conditional offers saying I had to complete my pre-req by a certain date (June). I think generically, most of the conditional offers just state that you have to finish your current degree with a certain GPA, for Queen's it was a 2.7 The average to get accepted is much higher than the grades you have to maintain in order to keep your acceptance.
For now I would focus on maintaining the great grades you have into the Fall, as those are what they will see when they make the initial admission decisions. If a decision isn't made prior to your Winter 2021 grades becoming available, they may factor those in, so you would want to try your best even with the hard courses you're planning on taking.
Try not to stress too much