When can I use 'on' before any date or day?
I know you use on before a day or date.
I can't distinguish when do I have to use on or don't.
For example, you don't say "See you on tomorrow.", but you say "see you tomorrow."
And do you say "I'll start this work on Sunday." or "I'll start this work Sunday."?
or Don't you use on before Sun-Sat day?

Thank you for your help.

Question

When can I use 'on' before any date or day?
I know you use on before a day or date.
I can't distinguish when do I have to use on or don't.
For example, you don't say "See you on tomorrow.", but you say "see you tomorrow."
And do you say "I'll start this work on Sunday." or "I'll start this work Sunday."?
or Don't you use on before Sun-Sat day?

Thank you for your help.

Answer

Hello Suhyun,
You can use 'on' for any day or date so 'I'll see you on Monday' or 'I'll see you on the 21st (June) are both correct. Also 'I'll see you on Christmas Day.' We use 'at' + time/holidays 'I'll see you at 6' or I'll see you at New Year.'  and finally we use 'in' + period of time. ..in December, in the 1970s, in 1993, in the summer.

Incidentally we would say "See you later today',  'See you tomorrow/next week/next month/next year.' all without a preposition.

Hope this helps

Bob

Answer

You would use 'on' for days in a basic sense. 
See you on Monday
See you on Tuesday
See you on Friday

When we specify WHICH specific day, you don't
See you next Monday
See you next Tuesday
I saw him last Wednesday

There are no prepositions before tomorrow, yesterday, today.

Answer

you can use 
in for months
on for days
at for hours

and about ur example
See you on tomorrow.", OR "see you tomorrow."
the both are correct

Answer

Both "I'll start this work on Sunday" or "I'll start this work Sunday are okay. Typically on can be used for the different days, such as Monday, tuesday, wednesday etc.

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