it depends on how long you have as a slot, and how much you can use info you already have to start it off - and how you are going to present the work. I've got one to do for a few weeks time, and I'm planning on a day to get the bare bones down, plans, basic info, and diagrams etc, and a day to add the meat - quotes, etc. (i've also got to persuade one of my techs to get an experiment ready for me to take along, but that's another story entirely). I have done one in an evening though, but I knew exactly what I needed to put in, so it was just a question of putting it together. you might be able to get some of it done and then slot in the results when you have them.