Why would that waste any days? If you paid for sub, you have an “end” date. If you have the token available, it will take over as your sub on the next day. You’ll have to keep farming gold to buy a token in advance from then on as well, since you won’t be using a card of any kind.
You won’t “waste” any days, they always add stuff to the end of your current time. My sub date has changed multiple times over the years using both the 6 month sub, but also being awarded time from buying expansions, which gives you a “free” month. I used to be set for January and July, but now I think I’m at May and November from all the shifts.
Answer from above: