Rental Investing Business Setup

[Tobin Short]

Been researching a while and looking through the threads. Sorry if this was already answered by many of you. 

I'd like to start investing in rental properties, but am completely unsure of how to set it up as business or when I should.

I'm aware I should AT LEAST have a separate/certain card to all of my expenses on and have some sort of filing system to note them (quickbooks, excel, etc.).

But when did most of you open a business account, setup an LLC or some other organization to operate under? Is this required? How many properties did you own until you set it up, or if you didn't, then why? Should I have an LLC setup prior to buying and renting out a home?

Also, I plan on mainly purchasing remotely, site unseen, and having property managers, even for homes that are local to me. 

Thank you.