If you're unsure about the freshness of your baking powder try this test. Put one teaspoon in 1/3 cup of water. If the water does not fizz toss the baking powder. It's too old.
There are a few different ways to poach an egg, and the time it takes to do so depends on your method and how runny or hard you'd like your yolk.
The first way to poach an egg is the "open pot" method. Add a generous splash of vinegar and a dash of salt to a medium-sized pot half-filled with water. (The proportions of this are not as important as your ability to reach in the pot.) Bring this to a good boil. Break an egg into a bowl and then slip the egg out of the bowl and into the water. This keeps the egg mostly in one place without too much spreading out. In two minutes, the whites are still a little runny around the yolk. After about three minutes, the whites will be completely done and the yolks will be mostly to moderately runny. After five minutes, the yolks are mostly hard.
The second way to poach an egg is with an open-steam egg poacher. This looks like a tray with round indentions that fits the top of a shallow pot. There are little holes in the tray that allow the steam to go over the top of the eggs. for these, you need to lubricate the indentions with butter or oil, break the eggs into the indentions, put a little bit of seasoning on top (salt, pepper, etc.), and then place the tray on top of the shallow pot in which water is already fully boiling. Cover the pot, wait exactly three minutes, and the yolks will be pink on top and mostly runny.
The third way is with a closed egg poacher. It looks like a ceramic jar with a lid. Prepare your eggs in the same way that you do with an open-steam poacher (one per jar), put the lid on, and place them in fully boiling water. Three minutes, again, brings about a mostly runny yolk. When you pull it out of the water, however, it's important to put the ceramic in a lukewarm water bath to cool the poacher and stop the egg from cooking.
A poached egg, incidentally, is the preferred method of preparation in making Eggs Benedict. Eggs Benedict starts with a toasted English muffin topped with a slice of grilled ham, then the poached egg is laid on top, and the whole thing is covered with hollandaise sauce. It is a very rich, delicious breakfast.