Since you bought Shimano SPD shoes, you might want to look into the Shimano dual-sided pedal.........it's perfect for first time clipless users and commuting/MTB'ng. One side of the pedal is a clip, the other side is a platform with a recessed area the cleat fits into but you don't clip in. That way you can always ride the platform side if you're feeling a little "iffy" on the clip side.
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"