Have a look at the article posted on Eye on Spain entitled 'Licence of First Occupation and Completion' if you are thinking of pulling out.
My reading is that you can get your money back + compensation??? if the developer fails to deliver the site on time  with FOL.
The direct  web address is www.eyeonspain.com/spain-magazine/licence-first-occupation.aspx
The lawyer who posted it might be quite busy.......!