回複：回複：B2 is bit different. Do you declare

I would suggest leave US before I-94 expiration date because the chance of change status from undeclared B2 to F1 is very low. If F1 application is denied, your out of status date will be counted from the next day of B2 I-94 expiration date. I would be safe to apply for F1 visa overseas like Mexico and Canada, or even China.