I almost always start our sore, stiff, slow and weak. I'm usually better by about five minutes, and feeling on top of my game maybe ten minutes into the ride. Some of this is stiffness being pushed away, some of it is shifting from a sugar burn to a fat burn, which is a lot more comfortable and less oxygen consuming (second wind), and some is from getting out of the house and back onto the bike. Being in the moment sharpens everything up, and makes me happy. I trust that the first five minutes will get better, and it always does.