not advisable as my friend in same situation was send back. he had 4000 cad cash but Immigration officer said 1-2 months is ok but why so early so he was send back and came only month before class. Depends on officer but why take risk.
I would agree that even with 4k arriving 4 months early might be a stretch just depends on the CBSA officer at the time given it would be a hard sell to be convincing no work would be necessary in that time. Even though there are no written rules how early funds would soon get depleted with accomodation and living costs.
Easier to justify 1-2 months early arrival purely on the pretext of getting established before courses start but 4 months needs a convincing case.
Add to that whilst being turned back would probably be some sort of voluntary turnaround and not an actual involuntary entry refusal but it still goes on record even though would not affect anything in the future just a risk not worth it. Plus an unecessary travel expense.