@yd1201 the only time this should happen is if you commit to one school…and then get off of a waitlist at a preferred school.
Is that what you are talking about?
College B (backup) - offer sent at May 1 with 14 days to accept
For regular decision colleges, as noted above, you will receive your acceptances well before May 1…and you will have until May 1 to make your choice of colleges.