Is this the right time for fast food business?

Good selection but risky at the moment, fast food is cheap but the bigger places like mcd's etc will get alot of the trade. You could try Smoothies and herbal teas, keep the menu simple. In my opinion I wouldnt open my own business yet, I had a similar idea though not food although the mark up is very good but was advised not to do anything yet, if the bigger stores cant survive neither will the smaller ones