Have you bought from Apple refurbished before? It’s practically like new set. If I’m a 2nd hand phone buyer I will chose it over a 1 year old used set.
I will choose refurbished if price is the same as 1 year old used for sure!
Have not buy refurbished before. But If were a 2nd hand phone buyer I will pay no more than a minimal premium for it. Technically there is no way for you to find the actual "Activation date" for any iphones.
Only thing that you could do is provide your invoice when apple sells/exchange a refurbish set for you.
To sum it up, it all round down to price.
I was a hunting a used iPhone 8 Plus 256GB about 3 months back. I bought a used one for $275, age of phone unknown so i'll assume it's release day set. Using it daily for work, smooth like butter no lag or flaws whatsoever (Maybe I am lucky.)
Some arrogant guy selling his "Tip top condition" iPhone 8 Plus 256GB Product Red for $499. Till today still unsold
The used market is very simple. People who hunt for older phones will look for the cheapest price with the best condition. Unless your price for your "perfect condition" phone is on par with the market rate or at most $50-100 extra. The interest will be low.