I suspect Mogg would have as well had MV3 actually happened. That said, I think May would’ve pulled it earlier this week even if Bercow hadn’t intervened.
The EU has already suggested that end June is not really an option so either May 23rd (2 months) or end 2019.
I remember when they asked Jack Straw the same question. His reply was somewhat different. He simply said they got it wrong and hadn’t thought more than a few thousand would come.