I manged to complete the MEIR, full time, in just over 2.5 months.
It's different for every person of course. The biggest obstacles you'll face will more than likely be based on:
- Study/training progress - just how capable you are and if minimums will suffice.
- Adverse weather - even the IR is susceptible to fog etc.
- Availability of resources - if your training provider is full and you're being shuffled in between other students, delays have a knockon effect.
Like all training, it seems insurmountable at times but wonderfully easy at the end... when you have the coveted licence in your hand.
Good luck and try to enjoy.