There is some good advise in FCOM chapter 6.10. Doesn't hurt to re-read it from time to time.
As mentioned above around 50' shift your focus to the end of the runway, somewhere between 20 and 30' start your flare and slowly start to reduce thrust. Ideally you reach idle at main gear touch down. Don't just chop it, that is a pretty sure way to produce less than ideal results especially with low experience on type. Don't be too slow either and don't flare too long, that will just use up a lot of perfectly usable runway.