Wanting to Trade In my Samsung S20 FE

Hola,

I am wondering if I can just trade in my Samsung S20 FE for an iPhone 15 Pro in a few months? I have never done a trade in/upgrade with T-Mobile even though I have been with them for years. I usually always get an unlocked phone from Samsung or Apple (I have an iPhone 12 as a backup right now). I do not want my hopes of upgrading/trading in to be dashed. I can wait between July and October. Can anyone help explain how the trade in/upgrade works? I have seen the prices for the iPhone 15 Pro change between 11 bucks and 35 bucks. It confuses me to an extent. I would love to get the iPhone 15 Pro before it leaves the shelves of T-Mobile.