Depends how you want to play and prioritize.
Most people who are pay-to-win or even cheap-to-play seem to want to put their emblems on their defense. They have 500 emblems, they want to make their 5* into a 5*+8. Essentially a 5.4* or a 5 and one-third star, if you will.
I prefer to spend my emblems on offense, not defense. I put 500 emblems on my 4*. This adds 100 power to them, essentially turning them into 5* equivalents.
So all those defending 5* that have gone up by one-third of a level on defense, my offensive hero 4* have all gone up by a full-level equivalent. I’m finding it so much easier to kill 5*+8 teams than I did before emblems came out. Love that everyone is focusing on taking a year plus to put emblems on their defenses.
That said, once defenses reach +18 or +19 of +20, they will be 90/95/100 power higher than a plain 5*. And then it will be back to the full level gap for me. But I’ll have enhanced 30 heroes with the same amount of emblems that others have advanced 10 of their 5*. So I still feel good about the approach.
With Khagan in your defense, and with you as a CTP, then perhaps you may wish to prioritize giving him the emblems. In which case I’d reset your Triton+7 and go all the way, if that’s your style - transfer those precious emblems from Triton to your Khagan as well.