Do I really need to start an LLC for a real estate investing company from the start?

I am trying to start a new real estate investing company in Illinois and am wondering what type of business entity to establish. This is a ground up company with myself as the sole proprietor. I intended to file a DBA but my CPA advised me to start an LLC instead. I have no ets and wouldn't have much of an operating capital to begin with. My thought is to start small with a DBA (sole proprietorship) and incorporate at a later date once I start to build capital. I think that it would make a bit more financial sense not to incorporate right away should the plans for the company not go as planned. I have made a few investments for the business (training courses, advertising, milage, etc.) which I ume I can write off as a sole proprietor. Any help would truly be appreciated. THANK YOU!!!