In reply to Kerry Webster.

Glad I'm not the only one. Their about page says 18-19 and the most recent blog post says 18-20. The reason for the confusion is that it is Saturday, Sunday, and Monday in different parts of the world at different times. For example, here are the start times for the Live Chat.

Sydney AEST GMT+10 Sun 05:00
London GMT Sat 20:00
Eastern GMT-4 Sat 15:00
Pacific GMT-7 Sat 12:00

When it wraps up, it will be Sunday in most places but Monday in Australia. Don't know if this helps. I did change the dates to 18-20