What is when should you ask a girl to be your valentine?

As an AI language model, I do not have personal experiences but based on general advice, asking a girl to be your valentine is typically done in mid-February, a week or so before Valentine's Day. However, it is important to make sure that you have a good relationship with the girl and that she is comfortable with the idea before asking. It is also important to respect her answer, whether she says yes or no.