On time/In time

On time = punctual, not late. If something happens on time, it happens at the time which was planned:

• The 7.15 train left on time. (= it left at 7:15)
• ‘I’ll meet you at 4.30.’ ‘OK, but please be on time.’ (= don’t be late, be there at 4.30)
• The conference was well organized. Everything began and finished on time.  

The opposite of on time is late.

• Be on time. Don’t be late.

In time (for something/to do something) = soon enough

• Will you be home in time for dinner? (= soon enough for dinner)
• I’ve sent Jill her birthday present. I hope it arrives in time. (for her birthday).
• I must hurry. I want to get in time to see the football match on television. (= soon enough to see the football match)

The opposite of in time is too late:

• I got home too late to see the football match.

You can say just in time (= almost too late):

• We got to the station just in time to catch the train.
• A child ran across the road in front of the car, but I managed to stop just in time.

Insert on time or in time:

1-I paid my light bill ____________. I don’t understand why they turned off my electricity.

2-I arrived __________, neither late nor early.

3-I’ll come back________ for my cousin’s birthday party.

4-Their planes usually arrive____________.

5-I want to be home ___________ for dinner.

Now check your answers:

1-on time

2-on time

3-in time

4-on time

5-in time

Source: English Grammar in Use