what day are you supposed to ask someone to be your valentine??

people tell me that it's before, others tell me its the day of. i thought its the day of too. what do you guys think??

note: shes my friend and i have a crush on her so its that kind of "proposal" (for a lack of better words lol) not asking to be my gf or anything but to gauge if she would consider going out w me or like me yk??