Depending on what Pokemon you do, it shouldn't take that much time. You could do a set only write up, for example Tabuu attempted at Agility Lucario but I think he gave up because he got lazy or something. I'll give you the quick rundown of a typical analysis:
First you write up a skeleton consisting of bullet points and important information that quickly summarizes points (this probably takes the longest because you have to calc stuff, test different sets, experiment, etc.) After you get 2/3 QC checks, then you're able to write a full blown analysis like the ones you see in the main Strategy Pokedex. After you get your final QC check which proves that there's enough information to suffice for the analysis, you have to get GP or Grammar checks. After 2 Grammar checks, your Analysis is finished and replaces the old analysis on the Pokedex!
So yeah it's time consuming, but you have plenty of time to finish it. You could tackle certain parts of the analysis every day, and they give you like 2 weeks to form your Skeleton into an analysis, which is pretty much the same but in complete sentences. Anyways if you ever wanted help writing one I could show you how to do it and even test some sets out for you.