The stationary bike practice can be useful, but you can do that on your commute, too. On straight, smooth, low-threat area, practice unclipping and clipping in, one foot at a time, while you ride. To start with, coast, unclip, clip-in, pedal a few strokes, and then repeat on the other side. Work up to doing it without stopping pedaling with the other foot.

It's a repetitive muscle-memory practice. It just takes time and repetition.