I'd say skipping all the admin part of joining a new company and whatever other admin. You could start day 1 at a flying school and come out 13 months later with a frozen ATPL and 200-250hrs, then walk into BA and start ground school for a month, then a month of sim training, and then a month of line training, extremly ball park with the standard days off and rostering once you started at BA so 15 months in the seat 16 checked out.
Now if you were doing the MPL (Multi-Crew Pilots License) from 2007 it looks like you do a PPL, ground school and then hop in the sim for your 200-250hrs and then start line training, so you could be in the seat in a lot less than a year as you can fly the sim 24/7 in any weather.
Found some info about the MPL here
http://www.swiss-aviation-training.c...dex/newsletter