I just installed NOS tubes?

My experience with tubes isn't as extensive as other A'Goners, but I've noticed with both my Blue Circle BC21 and Kora Hermes that whenever I changed the stock tubes to NOS to varying degrees I could always hear an immediate difference.

Tubes don't seem to need as much time as other components to "break-in", and I've also noticed that some go through drastic character changes before finally settling in. In my limited experience, 48-96 hours sounds about right.

I purchased them from Upscale Audio for $65.00 each. Initially the sound was comparable to the stock tubes but in another 2 hours the sound began to change especially in the mid-range. More detail so far.

I use NOS in my CJ premier 14, I notice a change immediately when I switch out. I go back and forth between stock and NOS.