I've been using TransX for about a year now and I've never really given much thought to that "T to Mnvre" line. The line right below it, "Begin Burn", obviously tells you when to perform the burn, so I've always been able to perform the burn at the right time.
Since this question was brought up in this thread, I took a look at one of my video recordings and I see exactly what N_Molson is saying.
I would re-explain it this way.
If you have to burn for 100 seconds, then you will start the burn (Begin Burn) when T to Mnvre is 50, and the burn should end when T to Mnvre is -50. So, one-half of the burn is done before reaching the precise maneuver point, and the other half of the burn is done after the precise maneuver point.
So the burn should be symmetrical.
Burns with the Align plane MFD work the same way. The information just isn't presented the exact same way.