As with the number games from a few weeks ago, pose problems for your child to solve using their clock.
“What is 1 hour more than 4 o’clock?” (They must make the clock say the correct time.)
You make the clock say a time, then give it to your child saying, “Move the clock on 3 hours.”
Just like other concepts, more/after is easier than less/before.
Therefore, once your child is comfortable with this, pose before problems such as;
“What time is it 2 hours before 12 o’clock?”
Show them the clock saying 9 o’clock, then ask, “Make the clock say 1 hour earlier?”