This type of talk is simply insane.
NO SCHOOL can guarantee you an IR in a set time
Harsh but I'm inclinded to agree at least in part ( and the other good advice that has been given here)- the IR is not an attendance course.
I see the IR very much as a licence to learn and have very experienced pilots willing to mentor me and fly IFR trips with me after my training.
Well your examiner certainly will not see the IR as a "licence to learn". He/she is going to be certifying you to go off and fly approachs to minima, possibly with other (possibly unsuspecting) souls on board.......
If you can, do yourself a favour and remove the time pressure - and however you go about it, good luck