1 way to tell- Do you still have the old tailpiece and p trap? if so, measure the tailpiece and see if it could have been shortened 2-3".
A 16" above the floor rough in usually works for most sinks. You said you're at 12" inside the cabinet- add the 4" toe kick and your right at 16"
But you can move the tee down relatively easily as it's ABS- Getting to the pipe is the biggest hurdle. After that it's simply cutting the pipe, unless the tee is off to the side of the window- then it gets difficult... Is it a tee or a 90?