I would not use "see you on time" "See you then" is better Also you use later, not late, when telling someone to not come after a certain time See you no later than 9:00

You are correct that the phrase is "to be on time". So you can say: "Please be on time!" When you specify a time, use "at". For example: "See you at 8" (that is, 8 o'clock), "See you at noon", "See you tomorrow at 6pm". You can put these together like this: "See you at 8. Please be on time: don't be late!" Or for added emphasis, you can add "sharp" after the time. For example: "See you at 8 sharp" "See you at 6pm sharp".