I have had a little search in the files, and have found some information relating to the end date and time of the event, The Greatest Little Quahog Circus:
End Date: 10/05/2014 (or 05/10/2014 for the american readers)
End Time: 23:59
If you play or have played the similar game to Family Guy : The Quest for Stuff, you will know that what the game files say regarding event times and dates can always change and sometimes do not reflect the real end date and time, just thought I would let you know what I have found – BUT if this is true, we would really have until the end of next Saturday…
My advice would be to keep collecting until the date and time is confirmed officially.