Okay two things:
FIRST THING: if your fanbase is small, there's Literally No Reason for anyone to release your patreon content for free. If you don't have hundreds of thousands of people clamouring for your work, who would they be releasing it to? Like, if you have ten fans, nobody's gonna be like "bwahaha, I'm gonna pay a dollar a month so I can share this exclusive content on reddit against the artist's wishes" because reddit will not care.
This only happens when you have a large enough fanbase that there are tons of people who WANT the patreon content really badly, large enough that you can easily find those people on some other site. It's actually the opposite of what you're thinking -- if you're big, your fanbase is too big to police 100%; if you're small, you have what computer people call "security through obscurity." Your work is more safe when your fanbase is small.
SECOND THING: If you're scared of people pledging, looking at content for free, and then backing out like @Lucazu mentioned , patreon now has an option where you can charge patrons up front -- making it so that as soon as people pledge, they have to pay their first pledge before they can look at any of your stuff. So it's possible to set up your patreon so that people have to pay before they can see your content.
I don't think it hurts to wait on a patreon (obviously I waited a while on mine!) but I just don't see any evidence that thievery is going to be your biggest concern when you're starting out.