prepositions - Be somewhere "on time", "at that time" or "in time"?

Do both imply the same meaning?

1. John told me to be there at 6pm. I will be there on time.


2. John told me to be there at 6pm. I will be there in time.



3. John told me to be there at 6pm. I will be there at that time.

I can feel that in time needs a for or a to but am not sure. Like in I'll be there in time for the show to start. or I'll be there in time to see it. (on time won't work)

Answer

On time = punctual

in time = timely with respect to something which will happen or a situation that may arise.

The meeting starts at 10AM. Please be on time. Don't be late.

The train left at noon. I arrived at 11:45, but not in time to get a seat. The seats were all taken, and I had to stand in the aisle.

If we place the order now, the office furniture should arrive in time for the new employees.