It's actually even quite fast.
You could do faster if you had
- very good knowledge of the administrative aspects or ability and willingness to learn them all very quickly
- very good theoretical abilities
- all the money lined up so it won't delay you
- a bit of luck (for instance, starting at certain periods of the year could be less favourable)
Here is the fastest that I reckon anyone could go :
Month 1 : september : PPL theory and first flying hours
Month 2 : start of ATPL theory learning, PPL completed at the end of the month
Months 3, 4, 5 : subscribe to an ATPL theory school (having started to learn the subjects one month before), fly all your time building, get your night rating etc..
Months 6, 7 : CPL MEIR
Month 8 : MCC/JOC
I believe it physically impossible to do it any faster.
I've known people who did each of the above steps in the time I mentionned individually, but I don't know of anyone who has done all the steps at this pace.
For realistic values, you can add 2 months for ATPL theory, and another month for practical training, and here you go : 45 weeks
But ask your school : if you negotiate, ask in advance, etc.. they very well may be able to fasten things up, if you can keep up with the pace.