"If I understand this correctly, There will be a due bill if someone sells anytime before the 28th of April"
I don't know where you got that idea, but if you owned HQNT on the date of record, you are OWED the SNDH dividend shares. You can sell your HQNT shares anytime, but you are still owed your dividend and, no, there are no bills due.
One warning, however. Just because you are owed your shares doesn't necessarily mean you'll be getting them. If there is a large naked short as some suggest, then there won't be enough SNDH dividend shares to go around and some longs simply won't be receiving their dividend -- at least not on the distribution date.
