I usually take off from a base that is far enough so that, with 100% fuel, I can grab about 10k and accelerate to top speed before the target. I drop all in one quick pass. I usually am at 10k for a while before I reach the target, so my speed is normally maxed out when I calibrate. Due to the fact that the eggs are carried externally (causing a lot of drag), dropping one will result in significant speed gain, therefore throwing off your calibration. I suggest you drop them all on close-together targets, such as the hangars on the main pads (or big pads, i forgot what its called). I usually keep my RATOs and fire them after my drop, to make a quick escape. Or, if i am attacked on my way to the target, i dive a bit and fire the RATOs. You DO NOT need them for takeoff, they just make it a lot easier.
If you want to take off quicker, lower the flaps all the way. Hold the brakes and go to full throttle. When the engs are at full, release the brakes and you should accelerate faster, because the engines are already spooled up. When you get up, dont try to climb. Level off at about 100 feet and gain some speed if you can.
Hope this helps.
Also, if anything doesn't make sense, ask a question. I will answer it later. It is 1:21 in the morning and I dozed off while typing this.