Toning can actually happen quite quickly. As as you begin to start resistance training at least 2-3 times per week, your body will begin to recruit more and more muscle fibers on a regular basis. (If you're not in shape, your body isn't able to trigger the entire muscle for contraction.) Having high muscle fiber recruitment gives your body the 'toned' look, and that can begin to show after, I'd say, a few weeks to a month.
In terms of actual strength, that will more or less happen immediately (after a week or two), also due the reasons that I listed above.