Can I write off purchases for a company that doesn't yet exist?

[Kevin K.]

Hello, pretty self-explanatory question but I'll flesh it out a bit. 

I've been reading the bigger-pockets tax strategies book and it got me thinking...

I currently do not have any properties or any entities. However, I do have every intention of starting this endeavor sometime in 2018. I have purchased several books (recommended from this site) and have been working through them. Can these books be written off? What about if I visit properties for research or use any of the other mentioned strategies, do I first need to buy a company / create an entity?

Thanks!