http://pprune.org/forums/showthread.php?threadid=124049
How long will depend on the method used (as I have detailed in this previous thread), whether deep strip is required and the obvious factor how fast your painters paint and the quality/quantity of the equipment they are using
As a guide in my experience a straight all white paint on a B737, scuffing off the old livery without deep strip, will take 3 shifts of 6 to 8 men 8-9 hours each shift...the livery masking/application another 2 shifts depending on complexity and method of application - for a deep strip add at least another 3 shifts as the solvents are evil and it can be quite labour intensive work plus you have to go primer coat and possibly (usually) more than one coat of base colour
So for a good operation to do a B737 or a B747 deep strip and repaint/re-livery 4 days...clearly more than 1 shift a day and additional personnel on the 747...
Cost...just recently had a B737-200 scuffed and repainted white, two colour cheat lines and stencil body titles and tail logo $70K