Whenever possible both hands move simultaneously, the support hand thumb up with palm down flat against the the upper abdomen and toward the master hand side. The bladed master hand with fingers pointed down moves across the abdomen to clear the open front garment (jacket). For a closed front garment (buttoned front shirt, sweatshirt, t-shirt, etc.) the support hand would reach across the front of the body to grab and lift the garment ahead of and above the holster. You could also use both hands, support hand ahead of and master hand just behind the holster. While wearing a closed front garment where the support hand is occupied, ie. holding your 18 month old infant, run the straightened master hand thumb pointing in and along the outer seam of your pants, under the garment to lift it out of the way. You could also curl your master hand fingers, nails against the seam, to lift the garment.
Presentations from the holster have been taught as 3, 4 or 5 counts. Variations will also occur depending on the particular style of holster. I prefer the 4 count but, as was mentioned above, speed is a function of smooth and efficient motion. For the strong side belt secured holster:
Count 1, GRIP: master hand drops straight down onto the weapon, disengages any security devices and established the firing grip. Firing side elbow should stay as far back behind the rib cage as possible.
Count 2, LIFT: with the wrist as straight as possible, the master hand lifts the pistol straight up and out of the holster clearing the muzzle. Certain holster types may require a slight rearward rocking motion to remove the weapon, others may require that the weapon be pushed forward slightly.
Count 3, LEVEL: pivot the master hand toward the target to level the muzzle, this will drop the firing side elbow so that the weapon and forearm are now parallel to the ground. The wrist will be at the rib cage. If the pistol has a manual safety disengage it at this point if you can reach it. If necessary the weapon can now be fired from this position.
Count 4, PUSH: the muzzle straight toward the target or the appropriate extended ready position. As your master hand passes the rib cage the support hand secures its position in your 2-handed grip, use its thumb if you must to disengage the manual safety. The sights should rise into and intersect your line of sight to your point of aim. Avoid scooping or flycasting the muzzle toward the target, it's wasted motion.
Other examples of wasted motion: deep crouching, dropping or throwing either shoulder forward or backward. The only movement required to present the pistol from the holster is that of the arms and hands. Depending on your particular platform (stance) a slight shift of weight forward, by leaning the shoulders ahead of the hips, might also take place.
Practice the counts one at a time progressing from 1, to 1 & 2, then 1, 2 & 3, then 1, 2, 3, & 4. Then combine 1 & 2 and 3 & 4. Finally, put them all together with the goal being a single motion. Par time for an A zone hit on an IPSC target at 7 yards from concealment is 1.5 secs or less. With practice you should easily be able to achieve and be happy with under 1.75 secs.