I would say another thing to consider if you are looking at 6 month plus turnaround times on the grading is how you think the market for the card may change in that time.
Obviously a good playoff run would help boost the value and even if they loose this weekend it most likely won't lower it.
However, would a new season have started by then? Maybe a poor start or injury would lower it, or conversely a great start could raise it.
Will the hobby be the same then? Not living in the US I don't know what the prevailing opinion is on when there may be an improvement with the pandemic. Is there an expectation that everyone may be living more "normal" lives again by then and cards may have lost some popularity?
Not being a NFL collector I don't know if the above prices would be normal for this sort of RC or if they have had significant recent inflation.
Either way, I don't know the answers to any of those questions but just thought they are probably things that would be worth at least considering especially if grading turnaround times are that long. You should not really be considering what the current market situation is but what your best guess is the market will look like whenever you would expect to get the card back.
All the best with the decision.
(Oh and I know little about grading and actively avoid buying graded cards but from what I have seen the sub graded BGS slabs go for much more than the overall grade only ones.)