Cut the Notch
Make the top cut first and then the bottom. When you're making the bottom cut, adjust your hand to control the throttle with your thumb. If you meet the top notch perfectly, the wedge will drop out of the notch. But most likely you'll have to extend the cuts from either the top or the bottom so the wedge can drop free.
Use Wedges on Big Trees
If you have a tree that's more than 18 in. in diameter, go ahead and make your notch cut and begin the felling cut. Stop cutting as soon as you've penetrated far enough to pound wedges behind the bar. Leave the bar in the cut with the saw running, but lock the chain brake and tap in the wedges. Then finish the cut. Wedges will keep the saw from getting pinched in the cut if the tree leans back.
Make the Felling Cut
Score a line connecting the apex of the notch on both sides for a cutting guide. The back cut should be parallel and even with the apex of the notch. Then make the felling cut. The instant the tree begins leaning, pull the saw free, set the chain brake and walk away along one of your escape routes, keeping an eye on the tree so you can react if it doesn't fall the way you planned. Never take your eye off a falling tree.