Late Interview --- ESF Year 1 ?????

My boy just got a late interview chance at SJS (Year 1 ) by the end of this month......what does it means?
Whay it come so late??
I suposed lots of kids are withdrawing from the offers.....
Anyways, I heard that it would be a pretty high chance to get an offer if you do receive an interview. Is that true?
How about all those kids in the waiting list which SJS claims that is a long one.
My boy is in the Cat 2, it is a surprise to me to get an interview at this late stage of admission .....even it's a bonce to have a chance to interview, I am still having a high expection though.
Any advice????

Thanks million times!!

Mitchmama