My luck as E on upgrading AC33 this year (YYZ YVR) has been 1 out of 2, and that time I was able to upgrade both myself and Mrs. YVR. Saturday is probably the best day since there's less business travel.
I'd watch out for trying to book a Tango fare morning of (by Tango I assume you mean Tango+), as fares can go up quite a bit day of (or before) departure. Also, once you hit the 24 hour window, there may not be R space, so your upgrade will clear at the gate.
You can always buy your T+ ticket on Thursday morning and try to upgrade it. If the upgrade hasn't cleared by Friday morning then cancel it within the 24 hour window for a full refund.