It's really important that you cover the whole period, you should have an event or something to talk about for each decade in your time period. It doesn't have to be in chronological order but it might help you if it is, I appreciate this is difficult though if you are structuring your essay by theme. I can't remember how many themes I did but I know I definitely did religion, misogyny and the monetary gain from witch hunting and how political figures benefitted from witch hunting.
Make sure you put your argument in your introduction! State this straight away so the examiner knows how you're arguing , and you should have the same argument in your conclusion. I would also introduce your themes, historians and primary sources in your introduction.
Have 3 sources, one for each theme, but make sure you have at least two different type of source, e.g. a religious manuscript and a wood carving.
Make a separate document for a checklist to make sure you've covered the time period, you've included sources and source analysis, historian and historian analysis. It just makes it easier for you to keep track of where your at, this was really helpful for me because I didn't write my essay in order, I wrote my themes before I even started writing my introduction.
Also have another document for your bibliography, any website or book you find information from make sure you put it on there and then when your finalising your essay you can go through it and take out anything you haven't used.
It's super important to be organised because it's such a big essay and you can be overwhelmed with it very easily unless you can physically see everything you have done/need to do and it will help you keep on top of it better.
Good luck