Are you asking about speaking? There are three correct options for spoken English. For example, you could say: My flight is on the 12th of June. My flight is on June the 12th. My flight is on June 12th. The first and the second options are both normal in British English. The last one isn't often used in British English - it sounds quite 'short and snappy' and American to follow the number directly on from the month. Also note that we don't use the 'the' or the 'of' in written English.

In US English, the latter is much more common (in both formal and informal settings). The former sounds somehow quaint (except is set expressions like "the fourth of July"). Both are correct, though.

Hi Diana! "June 12th, 2019" is much more common in American English. It sounds very formal to say "The 12th of June." Have a great day!

In the US and Canada, June 12th is the common way to say it.

There are also a number of situations where it would be common to say “month, number”, for example answering a “What” question. What day is your birthday? May 26. What’s the last day we can reply? June 30. When are you leaving? On May 26th. May 26th