I called CBSA yesterday, she checked and stated there is nothing in the rules to state when one should arrive as long as valid POE and DLI has covid readiness plan. So confusing.
I did some heavy research on this topic and it turns out, is not really all that confusing.
Your Student TRV is valid and usable for travel from the moment it was issued to the moment it expire. That is a fact.
Now, because of the current situation of the pandemic, CBSA is simply
discouraging any discretionary (Non-essential) travel.
Additionally, outside of the context of the pandemic, students that wants to travel early, normally are people that are impatient to arrive to Canada and are willing to engage in illegal work to support themselves. These are the 2 main reasons why CBSA
WILL flag you if you try to travel early.
That being said; You don't break absolutely any rule by trying to travel early but by doing so, CBSA
WILL question you about your motives and depending on your answers and the evidence you produce to support your claims, they will determine if you can enter the country or if you have to return later, closer to the date when your classes start. (or if you can enter at all).
So in conclusion, if you arrive 4 months before the date when your classes start and when asked why you are there so early, you answer something like "Because i have free time and want to visit some tourist sites", you will most likely be denied entry because your reason will be deemed Non-essential. And also if you can't prove that you won't be engaging in illegal work to support yourself those extra months outside of the budget you declared while applying to your study permit, you will also be most likely bounced back.
So, What is a Non-discretionary (Essential) reason that can justify arriving early? That is for the CBSA agent to decide.