Couple of things you need to remember is that at flaps full the attitude is around 2.5 nose up, if flaps at 3, then attitude is at 5 nose up. So we know that its a nose up approach attitude
the basic idea of the flare in this aircraft is to arrest the descent rate. The attitude needs to change very little
When i hear the 40 callout, i check which keeps the descent going but reduces it to about 400/500 ft/min. The reason i check at 40 feet is because by the time i hear it and my brain processes it my hand pulls back on the stick when im around 30 feet.
Then around 20 i hold about half stick in to set the attitude to land. Once the attitude is set, let the aircraft land. Normally the attitude is around 5 degrees nose up, however since you look outside visually, id say you need to see most of the runway. (its impossible to tell you how much you should see)
As for the power, with a strong headwind i cut it at 20.
With little wind i let it tell me retard once, then cut it.
With a tailwind, bring the power back at 40.
All of this is ball park and every situation is different so dont take all this as the way to do it.
Small note on flare mode (its in your FCOM)
At 50 feet, the aircraft is in Flare mode. It memorises your pitch attitude and slowly lowers the nose at 30 feet. This lowering of the nose is so that you can slowly ease some backpressure in set the attitude to land. Basically give u some control of the landing.
Remember set the attitude and let it land, cut the power according to the conditions and things should get a lot easier.