I've come across more info on when Virgie Till teamed up with Sonny Til.
Seems that Sonny & the Orioles secured long tenure bookings in Miami in the summers of 1957 & 1958.
On both occasions, the group were booked (for up to 24 weeks) to appear on Cab Calloway's Cotton Club Revue at a Miami Beach hotel. On at least one of these occasions, Virgie accompanied Sonny on the trip (well, she was born in Miami though both her parents had passed by then).
If they first 'got together' in 1957, that would have made her just 16 years old !!!! No wonder, Sonny wanted people to think that she was his sister.