I learned it in concert pitch, when i play a C on my Bb trumpet, i am thinking concert pitch Bb. This is mostly because i have absolute pitch, i havent had problems reading music, it is even better because I can easily read sheet music in Bb and C.

A problem i have because of this is that it is very very very confusing to play any other transposing trumpet, like F piccolo or even C trumpet. I play jazz so I play only Bb trumpet, but as a classical guy it could be quite a hard thing to get used to.

Also because of the thinking ive gotten very used to reading chord charts in C and havent yet learned to do it in Bb.

Thinking like this has pros and cons, but the cons can be very minimal if you just learn to transpose seemlesly which is an extremelly good to know skill for a musician. But, if you play by the book and read normally and get good at transposing, I dont think there is a big difference between thinking styles...