I am first author on a paper, from start of project to publication it took about 4.5yrs. Writing the paper was very time intensive because it did not just involve writing but reading tons of other papers for references, and to be able to develop a frame for the paper. In addition, I had to spend a lot of my time teaching myself advance biostats to know which statistical tests to run , why to run that test, and how to run them and so I could sound coherent and educated when writing about them in materials/methods. It was a long process, but it sure taught me A LOT, and its always nice to look back on and know that there is a paper that says My Name et al., instead of being the et al. =)
If you have any questions you can always PM me.