A couple of corrections. It will take 40,000 reputation to hit Champion
So you need to have done more than hit 12K each week. You need to maximize your reputation gain by using an artifact quality token at 12970. That puts you at 13410 rep for a week. Persons who have done that or close will make Champion next week.
Folks if you use 14 Green and 13 Blue tokens, that will put you at 11970 reputation and the 13410 if you thereafter use a purple. So maximize this week and next if you haven't already.
Just save your extra rep tokens and hand them in after reset. The vendors will still be there even if the event is over. the gap between hero -> champion is 10k less rep then it took to get to hero. So its very easy to have enough rep tokens by the end of week 2.