"It's an aerobic sport, dammit!"
In other words a good aerobic engine is good, regardless of the event. What varies the most for a TT is the positional difference. I would recommend at least one session per week in your chosen TT position, and getting closer to the event I would incrementally increase this to 100% of training in TT position. Most important is doing the hard efforts in the TT position
. Pay close attention to how you hold your body during these - maybe check on a wind trainer mirror/camera how things are going. Excessive hip roll, flat back, head low etc.