What is the formal cut off date?  Is it the end of the month or the 3rd of the following?  I'm in a panic bc while i've done well in attracting the necessary critters and have only one to go, I have been completely unable to spot a Pegasus!  It's as though they are just not around.  Two friends even set their gardens up to attract it but that critter continues to elude.  I'm having high anxiety about failing this quest which is Intermediate and the first time I got up the nerve to actually attempt the level.  Anyway, thanks in advance...

I had the same problem spotting the Pegasus especially while going thru Chemo but I managed to spot one a few days ago.  Im pretty sure the cut off is the end of the month, then on the 3rd October Mike lets everyone know who won a pot & which one.

I was wrong re the finishing date I copied & posted below:

You can start a quest any time during the month, and the cutoff date for completing quests is always 23:59 GMT on the 3rd day of the following month, with the Lottery draw and announcement of winners on this page taking place one minute later at midnight GMT.

Don't panic.
I signed up for the August easy quest while on holiday knowing that I wouldn't be able to start it until 2nd September.
I completed the quest, entered the lottery and got a pot.

Thank you, Gillian!