Deviation from best glide speed will cause you to squander height and therefore time.
No, this is a common misconception. A decrease below your best glide speed will not cost you altitude, but distance. Best glide gives you the best distance forward for a given rate of descent. Minimum sink gives you the minimum descent rate for a given period of time, and will be found at an airspeed less than best glide. Generally your best glide speed approximates very closely your sea level Vy speed, whereas your minimum sink will generally be very close to your published sea level Vx speed.
Don't make the equation harder than it need be. You do not need to agressively push the nose over. You DO need to fly the airplane.