If you're really committed to making this transition happen quickly, you can go straight to a twin bed. The advantage here is that this bed will last until your child goes away to college, and maybe even longer.
Moving to a twin bed is more of a financial commitment. Bed frames, box springs, and mattresses all cost more than either one of the other solutions. However, investing in something of quality means you can skip the added toddler bed step and save money in the long run.